### `bindTemplate: BindChain` _(readonly)_
Shorthand for [`bind`](module_ui_template-Template.md#static-function-bind), a binding [interface](module_ui_template-BindChain.md) pre–configured for the view instance.
It provides [`to()`](module_ui_template-BindChain.md#function-to:ATTRIBUTE) and [`if()`](module_ui_template-BindChain.md#function-if) methods that initialize bindings with observable attributes and attach DOM listeners.
```typescript
class SampleView extends View {
constructor( locale ) {
super( locale );
const bind = this.bindTemplate;
// These observable attributes will control
// the state of the view in DOM.
this.set( {
elementClass: 'foo',
isEnabled: true
} );
this.setTemplate( {
tag: 'p',
attributes: {
// The class HTML attribute will follow elementClass
// and isEnabled view attributes.
class: [
bind.to( 'elementClass' )
bind.if( 'isEnabled', 'present-when-enabled' )
]
},
on: {
// The view will fire the "clicked" event upon clicking in DOM.
click: bind.to( 'clicked' )
}
} );
}
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L259)
### `class: string | undefined` _(observable)_
An additional CSS class added to the [`element`](#member-element).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L152)
### `content: ViewCollection` _(readonly)_
A collection of the child views that creates the balloon panel contents.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L96)
### `element: HTMLElement | null` _(inherited)_
An HTML element of the view. `null` until [rendered](module_ui_view-View.md#function-render) from the [template](module_ui_view-View.md#member-template). The class-level example above illustrates typical usage. The full description, fenced examples, and assignment note are in the block comment immediately above the `element` field in the source.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L135)
### `isRendered: boolean` _(readonly)_
Set `true` when the view has already been [rendered](module_ui_view-View.md#function-render).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L142)
### `isVisible: boolean` _(observable)_
Controls whether the balloon panel is visible or not.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L136)
Defaults to `false`
### `left: number` _(observable)_
The absolute left position of the balloon panel in pixels.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L112)
Defaults to `0`
### `locale: Locale | undefined` _(readonly)_
A set of tools to localize the user interface.
Also see [`locale`](module_core_editor_editor-Editor.md#member-locale).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L151)
### `position: 'arrow_nw' | 'arrow_ne' | 'arrow_sw' | 'arrow_se'` _(observable)_
The balloon panel's current position. The position name is reflected in the CSS class set to the balloon, i.e. `.ck-balloon-panel_arrow_nw` for the "arrow\_nw" position. The class controls the minor aspects of the balloon's visual appearance like the placement of an [arrow](#member-withArrow). To support a new position, an additional CSS must be created.
Default position names correspond with [`defaultPositions`](#static-member-defaultPositions).
See the [`attachTo`](#function-attachTo) and [`pin`](#function-pin) methods to learn about custom balloon positions.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L128)
Defaults to `'arrow_nw'`
### `t: LocaleTranslate | undefined` _(inherited)_
Shorthand for [`t`](module_utils_locale-Locale.md#member-t).
Note: If [`locale`](#member-locale) instance hasn't been passed to the view this method may not be available.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L161)
#### Related:
* [Locale#t](module_utils_locale-Locale.md#member-t)
### `template?: Template` _(inherited)_
Template of this view. It provides the [`element`](#member-element) representing the view in DOM, which is [rendered](#function-render).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L167)
### `top: number` _(observable)_
The absolute top position of the balloon panel in pixels.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L104)
Defaults to `0`
### `viewUid?: string` _(inherited)_
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L169)
### `withArrow: boolean` _(observable)_
Controls whether the balloon panel has an arrow. The presence of the arrow is reflected in the `ck-balloon-panel_with-arrow` CSS class.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L145)
Defaults to `true`
### `_unboundChildren: ViewCollection` _(protected)_
A collection of view instances, which have been added directly into the [`children`](module_ui_template-Template.md#member-children).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L180)
### `_viewCollections: Collection>>` _(protected)_
Collections registered with [`createCollection`](#function-createCollection).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L174)
### `_pinWhenIsVisibleCallback: () => void | null` _(private)_
A callback that starts pinning the panel when [`isVisible`](#member-isVisible) gets `true`. Used by [`pin`](#function-pin).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L160)
### `_resizeObserver: ResizeObserver | null` _(private)_
An instance of resize observer used to detect if target element is still visible.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L165)
### `_scrollListenerDomRoots: Array` _(private)_
The nodes the `scroll` listener of the currently pinned panel is attached to: `document` plus every shadow root hosting the positioning target or the limiter. Emptied by [`_stopPinning`](#function-_stopPinning).
A single `document` listener is not enough, because `scroll` is not `composed` — its event path ends at the shadow root it originated in, so not even a capturing listener on `document` sees a scrollable container living inside a shadow root.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L175)
#### Static properties
### `arrowHeightOffset: number` _(static)_
A height offset of the arrow from the edge of the balloon. Controlled by CSS.
```
┌───────────────────────┐
│ │
│ Balloon │
│ Content │ ╱-- arrow height offset
│ │ V
└──+ +───────────────┘ --- ─┼───────
\ / │
/ │
────────────────────────────────┼───────
^
>┼────┼< arrow height offset
│ │
│ ┌────────────────────────┐
│ │ │
│ ╱ │
│ ╱ Balloon │
│ ╲ Content │
│ ╲ │
│ │ │
│ └────────────────────────┘
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L867)
Defaults to `10`
### `arrowSideOffset: number` _(static)_
A side offset of the arrow tip from the edge of the balloon. Controlled by CSS.
```
┌───────────────────────┐
│ │
│ Balloon │
│ Content │
│ │
└──+ +───────────────┘
| \ /
| /
>┼─────┼< ─────────────────────── side offset
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L835)
Defaults to `25`
### `defaultPositions: Record` _(static)_
A default set of positioning functions used by the balloon panel view when attaching using the [`attachTo`](#function-attachTo) method.
The available positioning functions are as follows:
**North west**
* `northWestArrowSouthWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northWestArrowSouthMiddleWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northWestArrowSouth`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northWestArrowSouthMiddleEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northWestArrowSouthEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
**North**
* `northArrowSouthWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northArrowSouthMiddleWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northArrowSouth`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northArrowSouthMiddleEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northArrowSouthEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
**North east**
* `northEastArrowSouthWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northEastArrowSouthMiddleWest`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northEastArrowSouth`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northEastArrowSouthMiddleEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
* `northEastArrowSouthEast`
```
+-----------------+
| Balloon |
+-----------------+
V
[ Target ]
```
**South**
* `southArrowNorthWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southArrowNorthMiddleWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southArrowNorth`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southArrowNorthMiddleEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southArrowNorthEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
**South west**
* `southWestArrowNorthWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southWestArrowNorthMiddleWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southWestArrowNorth`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southWestArrowNorthMiddleEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southWestArrowNorthEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
**South east**
* `southEastArrowNorthWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southEastArrowNorthMiddleWest`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southEastArrowNorth`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southEastArrowNorthMiddleEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
* `southEastArrowNorthEast`
```
[ Target ]
^
+-----------------+
| Balloon |
+-----------------+
```
**West**
* `westArrowEast`
```
+-----------------+
| Balloon |>[ Target ]
+-----------------+
```
**East**
* `eastArrowWest`
```
+-----------------+
[ Target ]<| Balloon |
+-----------------+
```
**Sticky**
* `viewportStickyNorth`
```
+---------------------------+
| [ Target ] |
| |
+-----------------------------------+
| | +-----------------+ | |
| | | Balloon | | |
| | +-----------------+ | |
| | | |
| | | |
| | | |
| | | |
| +---------------------------+ |
| Viewport |
+-----------------------------------+
```
See [`attachTo`](#function-attachTo).
Positioning functions must be compatible with [`DomPoint`](module_utils_dom_position-DomPoint.md).
Default positioning functions with customized offsets can be generated using [`generatePositions`](#static-function-generatePositions).
The name that the position function returns will be reflected in the balloon panel's class that controls the placement of the "arrow". See [`position`](#member-position) to learn more.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L1268)
### `stickyVerticalOffset: number` _(static)_
A vertical offset of the balloon panel from the edge of the viewport if sticky. It helps in accessing toolbar buttons underneath the balloon panel.
```
┌───────────────────────────────────────────────────┐
│ Target │
│ │
│ /── vertical offset │
┌─────────────────────────────V─────────────────────────┐
│ Toolbar ┌─────────────┐ │
├────────────────────│ Balloon │────────────────────┤
│ │ └─────────────┘ │ │
│ │ │ │
│ │ │ │
│ │ │ │
│ └───────────────────────────────────────────────────┘ │
│ Viewport │
└───────────────────────────────────────────────────────┘
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L892)
Defaults to `20`
### `_getOptimalPosition: ( options: DomOptimalPositionOptions ) => ( DomPoint | null )` _(private)_
Function used to calculate the optimal position for the balloon.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L897)
## Methods
### `constructor( locale? )`
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L180)
#### Parameters
* `locale?: Locale`
### `attachTo( options ) → boolean`
Attaches the panel to a specified [`target`](module_utils_dom_position-DomOptimalPositionOptions.md#member-target) with a smart positioning heuristics that chooses from available positions to make sure the panel is visible to the user i.e. within the limits of the viewport.
This method accepts configuration [options](module_utils_dom_position-DomOptimalPositionOptions.md) to set the `target`, optional `limiter` and `positions` the balloon should choose from.
```typescript
const panel = new BalloonPanelView( locale );
const positions = BalloonPanelView.defaultPositions;
panel.render();
// Attach the panel to an element with the "target" id DOM.
panel.attachTo( {
target: document.querySelector( '#target' ),
positions: [
positions.northArrowSouth,
positions.southArrowNorth
]
} );
```
**Note**: Attaching the panel will also automatically [`show`](#function-show) it.
**Note**: An attached panel will not follow its target when the window is scrolled or resized. See the [`pin`](#function-pin) method for a more permanent positioning strategy.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L279)
#### Parameters
* `options: Partial`
Positioning options compatible with [`getOptimalPosition`](module_utils_dom_position.md#function-getOptimalPosition). Default `positions` array is [`defaultPositions`](#static-member-defaultPositions).
#### Returns
* `boolean`
Whether the balloon was shown and successfully attached or not. Attaching can fail if the target provided in the options is invisible (e.g. element detached from DOM).
### `bind( bindProperty1, bindProperty2 ) → ObservableDualBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L996)
#### Type parameters
* * `K1`
* `K2`
#### Parameters
* `bindProperty1: K1`
Observable property that will be bound to other observable(s).
* `bindProperty2: K2`
Observable property that will be bound to other observable(s).
#### Returns
* `ObservableDualBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `bind( bindProperties ) → ObservableMultiBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1074)
#### Parameters
* `bindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'element' | 'template' | 'top' | 'left' | 'destroy' | 'position' | 'class' | 'content' | 'render' | 'show' | 'hide' | 'attachTo' | 'locale' | 'isVisible' | 't' | 'isRendered' | 'viewUid' | 'bindTemplate' | 'createCollection' | 'registerChild' | 'deregisterChild' | 'setTemplate' | 'extendTemplate' | 'withArrow' | 'pin' | 'unpin'>`
Observable properties that will be bound to other observable(s).
#### Returns
* `ObservableMultiBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `bind( bindProperty ) → ObservableSingleBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L918)
#### Type parameters
* `K`
#### Parameters
* `bindProperty: K`
Observable property that will be bound to other observable(s).
#### Returns
* `ObservableSingleBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `createCollection( views? ) → ViewCollection` _(inherited)_
Creates a new collection of views, which can be used as [`children`](module_ui_template-Template.md#member-children) of this view.
```typescript
class SampleView extends View {
constructor( locale ) {
super( locale );
const child = new ChildView( locale );
this.items = this.createCollection( [ child ] );
*
this.setTemplate( {
tag: 'p',
// `items` collection will render here.
children: this.items
} );
}
}
const view = new SampleView( locale );
view.render();
// It will append
to the .
document.body.appendChild( view.element );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L298)
#### Type parameters
* `T: extends View`
#### Parameters
* `views?: Iterable`
Initial views of the collection.
#### Returns
* `ViewCollection`
A new collection of view instances.
### `decorate( methodName ) → void` _(inherited)_
Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event.
Read more in the [dedicated](../framework/deep-dive/observables.md#decorating-object-methods) guide covering the topic of decorating methods with some additional examples.
Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event.
For example, to cancel the method execution the event can be [stopped](module_utils_eventinfo-EventInfo.md#member-stop):
```typescript
class Foo extends ObservableMixin() {
constructor() {
super();
this.decorate( 'method' );
}
method() {
console.log( 'called!' );
}
}
const foo = new Foo();
foo.on( 'method', ( evt ) => {
evt.stop();
}, { priority: 'high' } );
foo.method(); // Nothing is logged.
```
**Note**: The high [priority](module_utils_priorities-PriorityString.md) listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority).
It is also possible to change the returned value:
```typescript
foo.on( 'method', ( evt ) => {
evt.return = 'Foo!';
} );
foo.method(); // -> 'Foo'
```
Finally, it is possible to access and modify the arguments the method is called with:
```typescript
method( a, b ) {
console.log( `${ a }, ${ b }` );
}
// ...
foo.on( 'method', ( evt, args ) => {
args[ 0 ] = 3;
console.log( args[ 1 ] ); // -> 2
}, { priority: 'high' } );
foo.method( 1, 2 ); // -> '3, 2'
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1159)
#### Parameters
* `methodName: 'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'element' | 'template' | 'top' | 'left' | 'destroy' | 'position' | 'class' | 'content' | 'render' | 'show' | 'hide' | 'attachTo' | 'locale' | 'isVisible' | 't' | 'isRendered' | 'viewUid' | 'bindTemplate' | 'createCollection' | 'registerChild' | 'deregisterChild' | 'setTemplate' | 'extendTemplate' | 'withArrow' | 'pin' | 'unpin'`
Name of the method to decorate.
#### Returns
* `void`
### `delegate( events ) → EmitterMixinDelegateChain` _(inherited)_
Delegates selected events to another [`Emitter`](module_utils_emittermixin-Emitter.md). For instance:
```typescript
emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
```
then `eventX` is delegated (fired by) `emitterB` and `emitterC` along with `data`:
```typescript
emitterA.fire( 'eventX', data );
```
and `eventY` is delegated (fired by) `emitterC` along with `data`:
```typescript
emitterA.fire( 'eventY', data );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L539)
#### Parameters
* `events: Array`
Event names that will be delegated to another emitter.
#### Returns
* `EmitterMixinDelegateChain`
### `deregisterChild( children ) → void` _(inherited)_
The opposite of [`registerChild`](#function-registerChild). Removes a child view from this view instance. Once removed, the child is no longer managed by its parent, e.g. it can safely become a child of another parent view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L387)
#### Parameters
* `children: View | Iterable, any, any>`
Child views to be removed.
#### Returns
* `void`
#### Related:
* [BalloonPanelView#registerChild](#function-registerChild)
### `destroy() → void`
Recursively destroys the view instance and child views added by [`registerChild`](#function-registerChild) and residing in collections created by the [`createCollection`](#function-createCollection).
Destruction disables all event listeners:
* created on the view, e.g. `view.on( 'event', () => {} )`,
* defined in the [`template`](#member-template) for DOM events.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L222)
#### Returns
* `void`
### `extendTemplate( definition ) → void` _(inherited)_
[Extends](module_ui_template-Template.md#static-function-extend) the [`template`](#member-template) of the view with with given definition.
A shorthand for:
```typescript
Template.extend( view.template, definition );
```
**Note**: Is requires the [`template`](#member-template) to be already set. See [`setTemplate`](#function-setTemplate).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L426)
#### Parameters
* `definition: Partial`
Definition which extends the [`template`](#member-template).
#### Returns
* `void`
### `fire( eventOrInfo, args ) → GetEventInfo[ 'return' ]` _(inherited)_
Fires an event, executing all callbacks registered for it.
The first parameter passed to callbacks is an [`EventInfo`](module_utils_eventinfo-EventInfo.md) object, followed by the optional `args` provided in the `fire()` method call.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L512)
#### Type parameters
* `TEvent: extends BaseEvent`
The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `eventOrInfo: GetNameOrEventInfo`
The name of the event or `EventInfo` object if event is delegated.
* `args: TEvent[ 'args' ]`
Additional arguments to be passed to the callbacks.
#### Returns
* `GetEventInfo[ 'return' ]`
By default the method returns `undefined`. However, the return value can be changed by listeners through modification of the [`evt.return`](module_utils_eventinfo-EventInfo.md#member-return)'s property (the event info is the first param of every callback).
### `hide() → void`
Hides the panel.
See [`isVisible`](#member-isVisible).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L241)
#### Returns
* `void`
### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired in a specific (emitter) object.
Events can be grouped in namespaces using `:`. When namespaced event is fired, it additionally fires all callbacks for that namespace.
```typescript
// myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
myEmitter.on( 'myGroup', genericCallback );
myEmitter.on( 'myGroup:myEvent', specificCallback );
// genericCallback is fired.
myEmitter.fire( 'myGroup' );
// both genericCallback and specificCallback are fired.
myEmitter.fire( 'myGroup:myEvent' );
// genericCallback is fired even though there are no callbacks for "foo".
myEmitter.fire( 'myGroup:foo' );
```
An event callback can [stop the event](module_utils_eventinfo-EventInfo.md#member-stop) and set the [return value](module_utils_eventinfo-EventInfo.md#member-return) of the [`fire`](#function-fire) method.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/dom/emittermixin.ts#L457)
#### Type parameters
* `TEvent: extends BaseEvent`
The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `emitter: Emitter`
The object that fires the event.
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: CallbackOptions`
Additional options.
#### Returns
* `void`
### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired in a specific (emitter) object.
Events can be grouped in namespaces using `:`. When namespaced event is fired, it additionally fires all callbacks for that namespace.
```typescript
// myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
myEmitter.on( 'myGroup', genericCallback );
myEmitter.on( 'myGroup:myEvent', specificCallback );
// genericCallback is fired.
myEmitter.fire( 'myGroup' );
// both genericCallback and specificCallback are fired.
myEmitter.fire( 'myGroup:myEvent' );
// genericCallback is fired even though there are no callbacks for "foo".
myEmitter.fire( 'myGroup:foo' );
```
An event callback can [stop the event](module_utils_eventinfo-EventInfo.md#member-stop) and set the [return value](module_utils_eventinfo-EventInfo.md#member-return) of the [`fire`](#function-fire) method.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L475)
#### Type parameters
* `TEvent: extends BaseEvent`
The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `emitter: Emitter`
The object that fires the event.
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired in a specific Emitter or DOM Node. It is backwards compatible with [`listenTo`](module_utils_emittermixin-Emitter.md#function-listenTo:BASE_EMITTER).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/dom/emittermixin.ts#L421)
#### Type parameters
* `K: extends keyof DomEventMap`
#### Parameters
* `emitter: Window | EventTarget | Node`
The object that fires the event.
* `event: K`
The name of the event.
* `callback: ( this: this, ev: EventInfo, event: DomEventMap[ K ] ) => void`
The function to be called on event.
* `options?: CallbackOptions & object`
Additional options.
#### Returns
* `void`
### `off( event, callback ) → void` _(inherited)_
Stops executing the callback on the given event. Shorthand for [`this.stopListening( this, event, callback )`](#function-stopListening:DOM_STOP).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L444)
#### Parameters
* `event: string`
The name of the event.
* `callback: Function`
The function to stop being called.
#### Returns
* `void`
### `on( event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired.
Shorthand for [`this.listenTo( this, event, callback, options )`](#function-listenTo:HTML_EMITTER) (it makes the emitter listen on itself).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L416)
#### Type parameters
* `TEvent: extends BaseEvent`
The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `once( event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed on the next time the event is fired only. This is similar to calling [`on`](#function-on) followed by [`off`](#function-off) in the callback.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L431)
#### Type parameters
* `TEvent: extends BaseEvent`
The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `pin( options ) → void`
Works the same way as the [`attachTo`](#function-attachTo) method except that the position of the panel is continuously updated when:
* any ancestor of the [`target`](module_utils_dom_position-DomOptimalPositionOptions.md#member-target) or [`limiter`](module_utils_dom_position-DomOptimalPositionOptions.md#member-limiter) is scrolled,
* the browser window gets resized or scrolled.
Thanks to that, the panel always sticks to the [`target`](module_utils_dom_position-DomOptimalPositionOptions.md#member-target) and is immune to the changing environment.
```typescript
const panel = new BalloonPanelView( locale );
const positions = BalloonPanelView.defaultPositions;
panel.render();
// Pin the panel to an element with the "target" id DOM.
panel.pin( {
target: document.querySelector( '#target' ),
positions: [
positions.northArrowSouth,
positions.southArrowNorth
]
} );
```
To leave the pinned state, use the [`unpin`](#function-unpin) method.
**Note**: Pinning the panel will also automatically [`show`](#function-show) it.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L361)
#### Parameters
* `options: Partial`
Positioning options compatible with [`getOptimalPosition`](module_utils_dom_position.md#function-getOptimalPosition). Default `positions` array is [`defaultPositions`](#static-member-defaultPositions).
#### Returns
* `void`
### `registerChild( children ) → void` _(inherited)_
Registers a new child view under the view instance. Once registered, a child view is managed by its parent, including [rendering](#function-render) and [destruction](#function-destroy).
To revert this, use [`deregisterChild`](#function-deregisterChild).
```typescript
class SampleView extends View {
constructor( locale ) {
super( locale );
this.childA = new SomeChildView( locale );
this.childB = new SomeChildView( locale );
this.setTemplate( { tag: 'p' } );
// Register the children.
this.registerChild( [ this.childA, this.childB ] );
}
render() {
super.render();
this.element.appendChild( this.childA.element );
this.element.appendChild( this.childB.element );
}
}
const view = new SampleView( locale );
view.render();
// Will append
.
document.body.appendChild( view.element );
```
**Note**: There's no need to add child views if they're already referenced in the [`template`](#member-template):
```typescript
class SampleView extends View {
constructor( locale ) {
super( locale );
this.childA = new SomeChildView( locale );
this.childB = new SomeChildView( locale );
this.setTemplate( {
tag: 'p',
* // These children will be added automatically. There's no
* // need to call registerChild for any of them.
children: [ this.childA, this.childB ]
} );
}
// ...
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L369)
#### Parameters
* `children: View | Iterable, any, any>`
Children views to be registered.
#### Returns
* `void`
### `render() → void` _(inherited)_
Recursively renders the view.
Once the view is rendered:
* the [`element`](#member-element) becomes an HTML element out of [`template`](#member-template),
* the [`isRendered`](#member-isRendered) flag is set `true`.
**Note**: The children of the view:
* defined directly in the [`template`](#member-template)
* residing in collections created by the [`createCollection`](#function-createCollection) method,
* and added by [`registerChild`](#function-registerChild) are also rendered in the process.
In general, `render()` method is the right place to keep the code which refers to the [`element`](#member-element) and should be executed at the very beginning of the view's life cycle.
It is possible to [`extend`](module_ui_template-Template.md#static-function-extend) the [`template`](#member-template) before the view is rendered. To allow an early customization of the view (e.g. by its parent), such references should be done in `render()`.
```typescript
class SampleView extends View {
constructor() {
this.setTemplate( {
// ...
} );
},
render() {
// View#element becomes available.
super.render();
// The "scroll" listener depends on #element.
this.listenTo( window, 'scroll', () => {
// A reference to #element would render the #template and make it non-extendable.
if ( window.scrollY > 0 ) {
this.element.scrollLeft = 100;
} else {
this.element.scrollLeft = 0;
}
} );
}
}
const view = new SampleView();
// Let's customize the view before it gets rendered.
view.extendTemplate( {
attributes: {
class: [
'additional-class'
]
}
} );
// Late rendering allows customization of the view.
view.render();
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L489)
#### Returns
* `void`
### `set( values ) → void` _(inherited)_
Creates and sets the value of an observable properties of this object. Such a property becomes a part of the state and is observable.
It accepts a single object literal containing key/value pairs with properties to be set.
This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.
In TypeScript, those properties should be declared in class using `declare` keyword. In example:
```typescript
public declare myProp1: number;
public declare myProp2: string;
constructor() {
this.set( {
'myProp1: 2,
'myProp2: 'foo'
} );
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L843)
#### Parameters
* `values: object & object`
An object with `name=>value` pairs.
#### Returns
* `void`
### `set( name, value ) → void` _(inherited)_
Creates and sets the value of an observable property of this object. Such a property becomes a part of the state and is observable.
This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.
In TypeScript, those properties should be declared in class using `declare` keyword. In example:
```typescript
public declare myProp: number;
constructor() {
this.set( 'myProp', 2 );
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L815)
#### Type parameters
* `K`
#### Parameters
* `name: K`
The property's name.
* `value: BalloonPanelView[ K ]`
The property's value.
#### Returns
* `void`
### `setTemplate( definition ) → void` _(inherited)_
Sets the [`template`](#member-template) of the view with with given definition.
A shorthand for:
```typescript
view.setTemplate( definition );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L408)
#### Parameters
* `definition: TemplateDefinition`
Definition of view's template.
#### Returns
* `void`
### `show() → void`
Shows the panel.
See [`isVisible`](#member-isVisible).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L232)
#### Returns
* `void`
### `stopDelegating( event?, emitter? ) → void` _(inherited)_
Stops delegating events. It can be used at different levels:
* To stop delegating all events.
* To stop delegating a specific event to all emitters.
* To stop delegating a specific event to a specific emitter.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L552)
#### Parameters
* `event?: string`
The name of the event to stop delegating. If omitted, stops it all delegations.
* `emitter?: Emitter`
(requires `event`) The object to stop delegating a particular event to. If omitted, stops delegation of `event` to all emitters.
#### Returns
* `void`
### `stopListening( emitter?, event?, callback? ) → void` _(inherited)_
Stops listening for events. It can be used at different levels:
* To stop listening to a specific callback.
* To stop listening to a specific event.
* To stop listening to all events fired by a specific object.
* To stop listening to all events fired by all objects.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L497)
#### Parameters
* `emitter?: Emitter`
The object to stop listening to. If omitted, stops it for all objects.
* `event?: string`
(Requires the `emitter`) The name of the event to stop listening to. If omitted, stops it for all events from `emitter`.
* `callback?: Function`
(Requires the `event`) The function to be removed from the call list for the given `event`.
#### Returns
* `void`
### `stopListening( emitter?, event?, callback? ) → void` _(inherited)_
Stops listening for events. It can be used at different levels: It is backwards compatible with [`listenTo`](module_utils_emittermixin-Emitter.md#function-listenTo:BASE_EMITTER).
* To stop listening to a specific callback.
* To stop listening to a specific event.
* To stop listening to all events fired by a specific object.
* To stop listening to all events fired by all objects.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/dom/emittermixin.ts#L481)
#### Parameters
* `emitter?: Window | EventTarget | Node | Emitter`
The object to stop listening to. If omitted, stops it for all objects.
* `event?: string`
(Requires the `emitter`) The name of the event to stop listening to. If omitted, stops it for all events from `emitter`.
* `callback?: Function`
(Requires the `event`) The function to be removed from the call list for the given `event`.
#### Returns
* `void`
### `unbind( unbindProperties ) → void` _(inherited)_
Removes the binding created with [`bind`](#function-bind:SINGLE_BIND).
```typescript
// Removes the binding for the 'a' property.
A.unbind( 'a' );
// Removes bindings for all properties.
A.unbind();
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1090)
#### Parameters
* `unbindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'element' | 'template' | 'top' | 'left' | 'destroy' | 'position' | 'class' | 'content' | 'render' | 'show' | 'hide' | 'attachTo' | 'locale' | 'isVisible' | 't' | 'isRendered' | 'viewUid' | 'bindTemplate' | 'createCollection' | 'registerChild' | 'deregisterChild' | 'setTemplate' | 'extendTemplate' | 'withArrow' | 'pin' | 'unpin'>`
Observable properties to be unbound. All the bindings will be released if no properties are provided.
#### Returns
* `void`
### `unpin() → void`
Stops pinning the panel, as set up by [`pin`](#function-pin).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L385)
#### Returns
* `void`
### `_startPinning( options ) → boolean` _(private)_
Starts managing the pinned state of the panel. See [`pin`](#function-pin).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L407)
#### Parameters
* `options: Partial`
Positioning options compatible with [`getOptimalPosition`](module_utils_dom_position.md#function-getOptimalPosition).
#### Returns
* `boolean`
Whether the balloon was shown and successfully attached or not. Attaching can fail if the target provided in the options is invisible (e.g. element detached from DOM).
### `_stopPinning() → void` _(private)_
Stops managing the pinned state of the panel. See [`pin`](#function-pin).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L469)
#### Returns
* `void`
#### Static methods
### `generatePositions( options = { options.config?, options.heightOffset?, options.sideOffset?, options.stickyVerticalOffset? } ) → Record` _(internal)_
Returns available [`BalloonPanelView`](module_ui_panel_balloon_balloonpanelview-BalloonPanelView.md) [positioning functions](module_utils_dom_position-PositioningFunction.md) adjusted by the specific offsets.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L504)
#### Parameters
* `options: object`
Options to generate positions. If not specified, this helper will simply return [`defaultPositions`](#static-member-defaultPositions).
Properties
* `options.config?: object`
Additional configuration of the balloon balloon panel view. Currently only [`withArrow`](#member-withArrow) is supported. Learn more about [positioning functions](module_utils_dom_position-PositioningFunction.md).
* `options.heightOffset?: number`
A custom height offset (in pixels) of each position. If not specified, [the default value](#static-member-arrowHeightOffset) will be used.
* `options.sideOffset?: number`
A custom side offset (in pixels) of each position. If not specified, [the default value](#static-member-arrowSideOffset) will be used.
* `options.stickyVerticalOffset?: number`
A custom offset (in pixels) of the `viewportStickyNorth` positioning function. If not specified, [the default value](#static-member-stickyVerticalOffset) will be used.
Defaults to `{}`
#### Returns
* `Record`
## Events
### `change:class( eventInfo, name, value, oldValue )`
Fired when the `class` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L152)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`class`).
* `value: string | undefined`
New value of the `class` property with given key or `null`, if operation should remove property.
* `oldValue: string | undefined`
Old value of the `class` property with given key or `null`, if property was not set before.
### `change:isVisible( eventInfo, name, value, oldValue )`
Fired when the `isVisible` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L136)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`isVisible`).
* `value: boolean`
New value of the `isVisible` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `isVisible` property with given key or `null`, if property was not set before.
### `change:left( eventInfo, name, value, oldValue )`
Fired when the `left` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L112)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`left`).
* `value: number`
New value of the `left` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `left` property with given key or `null`, if property was not set before.
### `change:position( eventInfo, name, value, oldValue )`
Fired when the `position` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L128)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`position`).
* `value: 'arrow_nw' | 'arrow_ne' | 'arrow_sw' | 'arrow_se'`
New value of the `position` property with given key or `null`, if operation should remove property.
* `oldValue: 'arrow_nw' | 'arrow_ne' | 'arrow_sw' | 'arrow_se'`
Old value of the `position` property with given key or `null`, if property was not set before.
### `change:top( eventInfo, name, value, oldValue )`
Fired when the `top` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L104)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`top`).
* `value: number`
New value of the `top` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `top` property with given key or `null`, if property was not set before.
### `change:withArrow( eventInfo, name, value, oldValue )`
Fired when the `withArrow` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L145)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`withArrow`).
* `value: boolean`
New value of the `withArrow` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `withArrow` property with given key or `null`, if property was not set before.
### `change:{property}( eventInfo, name, value, oldValue )` _(inherited)_
Fired when a property changed value.
```typescript
observable.set( 'prop', 1 );
observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `${ propertyName } has changed from ${ oldValue } to ${ newValue }` );
} );
observable.prop = 2; // -> 'prop has changed from 1 to 2'
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1190)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
The property name.
* `value: TValue`
The new property value.
* `oldValue: TValue`
The previous property value.
### `render( eventInfo, )` _(inherited)_
Event fired by the [`render`](module_ui_view-View.md#function-render) method. Actual rendering is executed as a listener to this event with the default priority.
See [`decorate`](module_utils_observablemixin-Observable.md#function-decorate) for more information and samples.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/view.ts#L538)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `: Parameters`
### `set:class( eventInfo, name, value, oldValue )`
Fired when the `class` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L152)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`class`).
* `value: string | undefined`
New value of the `class` property with given key or `null`, if operation should remove property.
* `oldValue: string | undefined`
Old value of the `class` property with given key or `null`, if property was not set before.
### `set:isVisible( eventInfo, name, value, oldValue )`
Fired when the `isVisible` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L136)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`isVisible`).
* `value: boolean`
New value of the `isVisible` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `isVisible` property with given key or `null`, if property was not set before.
### `set:left( eventInfo, name, value, oldValue )`
Fired when the `left` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L112)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`left`).
* `value: number`
New value of the `left` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `left` property with given key or `null`, if property was not set before.
### `set:position( eventInfo, name, value, oldValue )`
Fired when the `position` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L128)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`position`).
* `value: 'arrow_nw' | 'arrow_ne' | 'arrow_sw' | 'arrow_se'`
New value of the `position` property with given key or `null`, if operation should remove property.
* `oldValue: 'arrow_nw' | 'arrow_ne' | 'arrow_sw' | 'arrow_se'`
Old value of the `position` property with given key or `null`, if property was not set before.
### `set:top( eventInfo, name, value, oldValue )`
Fired when the `top` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L104)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`top`).
* `value: number`
New value of the `top` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `top` property with given key or `null`, if property was not set before.
### `set:withArrow( eventInfo, name, value, oldValue )`
Fired when the `withArrow` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/balloonpanelview.ts#L145)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`withArrow`).
* `value: boolean`
New value of the `withArrow` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `withArrow` property with given key or `null`, if property was not set before.
### `set:{property}( eventInfo, name, value, oldValue )` _(inherited)_
Fired when a property value is going to be set but is not set yet (before the `change` event is fired).
You can control the final value of the property by using the [event's `return` property](module_utils_eventinfo-EventInfo.md#member-return).
```typescript
observable.set( 'prop', 1 );
observable.on>( 'set:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `Value is going to be changed from ${ oldValue } to ${ newValue }` );
console.log( `Current property value is ${ observable[ propertyName ] }` );
// Let's override the value.
evt.return = 3;
} );
observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `Value has changed from ${ oldValue } to ${ newValue }` );
} );
observable.prop = 2; // -> 'Value is going to be changed from 1 to 2'
// -> 'Current property value is 1'
// -> 'Value has changed from 1 to 3'
```
**Note:** The event is fired even when the new value is the same as the old value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1228)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
The property name.
* `value: TValue`
The new property value.
* `oldValue: TValue`
The previous property value.
### `submit( eventInfo )` _(inherited)_
Fired by [`submitHandler`](module_ui_bindings_submithandler.md#function-submitHandler) helper.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/bindings/submithandler.ts#L61)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
---
Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)