I tried and no go:
From custom_config.js and config.js:
...
FCKConfig.FormatSource = false ;
...
FCKConfig.Plugins.Add( 'Splitter' ) ;
...
FCKConfig.ToolbarSets["standard"] = [
['Source','-','Preview','-','Templates'],
['Cut','Copy','Paste','PasteText','PasteWord'],
['Undo','Redo','-','Find','Replace','-','RemoveFormat'],
['Bold','Italic','Underline'],
['OrderedList','UnorderedList','-','Outdent','Indent'],
['JustifyLeft','JustifyCenter','JustifyRight','JustifyFull'],
['Link','Anchor','Splitter'],
['Image','Flash','Table','Rule','SpecialChar'],
['Style'],['FontFormat'],['FontName'],['FontSize'],
['TextColor','BGColor']
];
From editor/plugins/Splitter:
//Begin Code
var FCKSplitter = function(name)
{
this.Name = name;
}
FCKSplitter.prototype.Execute = function()
{
if(document.all)
{
mySelection = FCK.EditorDocument.selection
}
else
{
mySelection = FCK.EditorWindow.getSelection()
}
myTextRange= mySelection.createRange()
myText = myTextRange.text
FCK.InsertHtml(myText+"<hr />")
myTextRange.select()
}
// manage the plugins' button behavior
FCKSplitter.prototype.GetState = function()
{
return FCK_TRISTATE_OFF;
}
FCKCommands.RegisterCommand( 'Splitter', new FCKSplitter('Splitter')) ;
// Create the toolbar button.
var oEmphasisItem = new FCKToolbarButton( 'Splitter', "Splitter", null, null, false, true ) ;
oEmphasisItem.IconPath = FCKConfig.PluginsPath + 'Splitter/hr.gif' ;
FCKToolbarItems.RegisterItem( 'Splitter', oSplitterItem ) ;
//End Code