New Features:

• #835: Extended support for pasting from external applications:
  • Added support for pasting rich content from Google Docs with the Paste from Google Docs plugin.
  • Added a new Paste Tools plugin for unified paste handling.
• #3315: Added support for strikethrough in the BBCode plugin. Thanks to Alexander Kahl!
• #3175: Introduced selection optimization mechanism for handling incorrect selection behaviors in various browsers:
  • #3256: Triple-clicking in the last table cell and deleting content no longer pulls the content below into the table.
  • #3118: Selecting a paragraph with a triple-click and applying a heading applies the heading only to the selected paragraph.
  • #3161: Double-clicking a <span> element containing just one word creates a correct selection including the clicked <span> only.
• #3359: Improved dialog positioning and behavior when the dialog is resized or moved, or the browser window is resized.
• #2227: Added the config.linkDefaultProtocol configuration option that allows setting the default URL protocol for the Link plugin dialog.
• #3240: Extended the CKEDITOR.plugins.widget#mask property to allow masking only the specified part of a widget.
• #3138: Added the possibility to use the widgetDefinition.getClipboardHtml() method to customize the widget HTML during copy, cut and drag operations.

Fixed Issues:

• #808: Fixed: Widgets and other content disappear on drag and drop in read-only mode.
• #3260: Fixed: Widget drag handler is visible in read-only mode.
• #3261: Fixed: A widget initialized using the dialog has an incorrect owner document.
• #3198: Fixed: Blurring and focusing the editor when a widget is focused creates an additional undo step.
• #2859: [IE, Edge] Fixed: Various editor UI elements react to right mouse button click:
  • #2845: Rich Combo.
  • #2857: List Block.
  • #2858: Menu.
• #3158: [Chrome, Safari] Fixed: Undo plugin breaks with the filling character.
• #504: [Edge] Fixed: The editor's selection is collapsed to the beginning of the content when focusing the editor for the first time.
• #3101: Fixed: CKEDITOR.dom.range#_getTableElement() returns null instead of a table element for edge cases.
• #3287: Fixed: CKEDITOR.tools.promise initializes incorrectly if an AMD loader is present.
• #3379: Fixed: Incorrect CKEDITOR.editor#getData() call when inserting content into the editor.
• #941: Fixed: An error is thrown after styling a table cell text selected using the native selection when the Table Selection plugin is enabled.
• #3136: [Firefox] Fixed: Clicking Balloon Toolbar items removes the native table selection.
• #3381: [IE8] Fixed: The CKEDITOR.tools.object.keys() method does not accept non-objects.
• #2395: [Android] Fixed: Focused input in a dialog is scrolled out of the viewport when the soft keyboard appears.
• #453: Fixed: Link dialog has an invalid width when the editor is maximized and the browser window is resized.
• #2138: Fixed: An email address containing a question mark is mishandled by the Link plugin.
• #14613: Fixed: Race condition when loading plugins for an already destroyed editor instance throws an error.
• #2257: Fixed: The editor throws an exception when destroyed shortly after it was created.
• #3115: Fixed: Destroying the editor during the initialization throws an error.
• #3354: [iOS] Fixed: Pasting no longer works on iOS version 13.
• #3423 Fixed: Bookmarks can be created inside temporary elements.

API Changes:

• #3154: Added the CKEDITOR.tools.array.some() method.
• #3245: Added the CKEDITOR.plugins.undo.UndoManager.addFilterRule() method that allows filtering undo snapshot contents.
• #2845: Added the CKEDITOR.tools.normalizeMouseButton() method.
• #2975: Added the CKEDITOR.dom.element#fireEventHandler() method.
• #3247: Extended the CKEDITOR.tools.bind() method to accept arguments for bound functions.
• #3326: Added the CKEDITOR.dom.text#isEmpty() method.
• #2423: Added the CKEDITOR.plugins.dialog.getModel() and CKEDITOR.plugins.dialog.getMode() methods with their CKEDITOR.plugin.definition counterparts, allowing to get the dialog subject of a change.
• #3124: Added the CKEDITOR.dom.element#isDetached() method.