Modifying the editor dialogs is possible by following the Customize Built-in Editor Dialog approach, demonstrated in this live example
. In your case you should modify the SetImageProperties.ascx file and set properly the ExternalDialogsPath
property as suggested in the mentioned demo.
A similar actions is also described in this KB article
Executing further logic upon triggering dialog tools is not a matter handled by the OnClientCommandExecuting
or OnClientCommandExecuted events. These events are raised only when commands form the toolbar are executed.
To add some custom logic, you should again follow the dialog customization approach and define the desired logic with the possible event handlers.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.