Insert from DropDownList

Sure it's possible. But there isn't, AFAIK, an available toolbar drop-down that lets you insert arbitrary code.

I've written a plug-in that was designed to insert pre-defined HTML based on a valid form field list; it's not terribly difficult once you find the right bit of code to hook in to.

I started by looking at the Style drop-down code. It, in turn, uses FCKToolbarSpecialCombo as a prototype. If you have a static list of stuff you want to insert, you only need to define a CreateItems function that loads whatever source of items you have for the drop-down (XML, JavaScript object...), register your new item to the system per the standard plug-in for toolbar instructions and your plug-in is pretty much complete.

Create a 'mynewcombo' directory in the editor/plugins directory, create a 'lang' directory under that, create a lang entry for your language for 'MyNewCombo', then create the fckplugin.js file in the 'mynewcombo' directory:

var MyNewCombo = function( tooltip, style)
{
   if (tooltip === false )
      return;

   this.CommandName = 'MyNewCombo';
   this.Label = this.GetLabel() ;
   this.Tooltip = tooltip ? tooltip : this.Label;
   this.Style = style ? style: FCK_TOOLBARITEM_ICONTEXT;
   this.DefaultLabel = '';
}

MyNewCombo.prototype = new FCKToolbarSpecialCombo;

MyNewCombo.prototype.GetLabel = function ()
{
   return  FCKLang.MyNewCombo;  // Be sure to create a plugin lang directory and a language file for your plug-in
}

MyNewCombo.prototype.CreateItems = function ( target )
{
   // Add item code, specific to your plug-in - here's my basic framework minus the actual reading of each item...
   // while ( itemsToInsert ) {
   //    var item = target.AddItem( optionVal, optionText );
   //    item.Name = optionVal;
   //    item.Definition = HtmlToInsert;
   // }
}

var MyNewComboCommand = function() {}

MyNewComboCommand.prototype =
{
   Name: 'MyNewCombo';
   Execute: function( name, item )
   {
      FCKUndo.SaveUndoStep() ;
      FCK.InsertHtml( item.Definition );
      FCKUndo.SaveUndoStep() ;
      FCK.Focus() ;
      FCK.Events.FireEvent( 'OnSelectionChange' );
   },
   GetState: function()
   {
      if ( FCK.EditMode != FCK_EDITMODE_WYSISYG || !FCK.EditorDocument ) { return FCK_TRISTATE_DISABLED; }
      return FCK_TRISTATE_OFF;
   }

FCKCommands.RegisterCommand( 'MyNewCombo', new FCKMyNewComboCommand() );
var oMyNewComboItem = new MyNewCombo( 'MyNewCombo') ;
FCKToolbarItems.RegisterItem( 'MyNewCombo', oMyNewComboItem);

Add 'mynewcombo' as a plugin and 'MyNewCombo' to your Toolbar line in fckconfig.js and you're ready to rock and roll.

No, you don't need help, you need to learn basic good education.

LesBarstow has provided you with the code of a plugin to help you, he has explained the steps that you need to follow and you are demanding for a detailed step by step?

If you don't want to read the forums and the docs, and you need the code so badly that you can't wait even a single day, why don't you hire a developer?

The code I posted is a pretty complete framework for a generic toolbar combo-box plug-in. What you're doing to customize your editor is just that - custom. I'm already programming for my employer, and not getting paid to program here. Because FCKeditor is such a useful toolset to us, I like to contribute back to the community - for now, that's answering questions here on the forum. If I get some time, maybe it's enhancing the Docs Wiki to include some programming hints like I did here. Please think of extending the FCKeditor as what it is - programming to a (sometimes poorly documented, but pretty complete) API toolkit.

Take some time to read through the Developer Docs, especially the section on writing plug-ins, and you may also need to delve a bit into the source code if you want to find many useful functions that already exist in the editor code.