It is possible to register the external dialogs of RadEditor, as shown in this online demo: Customize Built-in Dialogs.
By default, all RadEditor dialogs are embedded as resource files in the Telerik.Web.UI.dll.
In order to provide an easy way to modify the editor's dialogs, the RadControls installation now comes with a folder named EditorDialogs
which contains all editor's dialogs files (including the image map dialog). With a default installation, you'd find this folder at "C:\Program Files (x86)\Telerik\RadControls for ASP.NET AJAX Q1 2012\EditorDialogs"
You can modify the "imagemap.ascx", replacing the url textbox with a droplist.
Finally, you can configure RadEditor to use the external dialog files by copying the EditorDialogs
folder to your web application and setting the ExternalDialogsPath
property to point to it, as in the snippet below:
I'm not sure how you can get access to the new droplist to populate your custom links from the database, but it looks like you may be able to get a handle on the dialog using the method specified in the Resizing RadEditor's dialogs
Hope this helps!