Hi mike,
In order to achieve your goal you have to edit the default template of the
RadExpander control. For more information you can take a look at
this article. When you extract it you will be able to find a
Path control named "
arrow". In your case you will have to replace it with an
Image control. Furthermore, you will have to customize the
VisualStates that change the control named "
arrow". In your case you will have to change the
Image.
Source property in the different states.
For your convenience I exacted and edited the default template in the attached project. Please note that I have replaced the
Path control with an
Ellipse for simplicity.
I hope this works in your scenario.
Regards,
Pavel R. Pavlov
the Telerik team