The control allows a good deal of customization. By modifying the CSS stylesheet, you can change the look and feel of the editor. By creating your own editor class and inheriting the editor control, you can specify which toolbar buttons should be available, and which panes to enable. Unfortunately, you can’t easily change the state of a toolbar button on startup. if it were possible to pre-set the ‘right to left direction’ toggle button from the server. The control’s server-side properties do not allow this, but I was able to help him find a solution
http://www.thecodepage.com/post/Change-the-default-state-of-an-AJAXControlToolkit-HTMLEditor-Toolbar-Button.aspx
{
AjaxControlToolkit.HTMLEditor.ToolbarButton.MethodButton btn=new AjaxControlToolkit.HTMLEditor.ToolbarButton.MethodButton();
btn.NormalSrc= "aa.jpg";
btn.Attributes.Add("onclick", "alert('a');");
TopToolbar.Buttons.Add(btn);
}
Download Change Set #54501 from http://ajaxcontroltoolkit.codeplex.com/SourceControl/ListDownloadableCommits.aspx .
Not a good idea to create custom buttons this way...
See the new example: /SampleWebSite/HTMLEditor/OtherSamples/EditorWithCustomButtons_1.aspx .
Also see: /SampleWebSite/App_Code/HTMLEditor.Samples.cs,
/SampleWebSite/App_Code/HTMLEditor.CustomButtonsAndPopups.cs .
There are new folders: /SampleWebSite/App_Scripts and /SampleWebSite/App_Images .
Refrence : http://forums.asp.net/t/1432800.aspx/1?anyone+got+AjaxControlToolKit+HTML+Editor+to+work+with+an+image+button+changes