Thank you for your feedback. For now we do not cover similar behavior. It is hard to predict what every single user would like to achieve. To support multiple images in a single button is not actually and option as we should nest unknown number of elements which should be manged and could cause functionality problems. If more people are interested in a similar behavior we will consider if this is possible to be done without to increase unnecessary the CSS and HTML and to decrease the control performance.
I think that for your scenario, you could use: Radios and Checkboxes Demo
where you could find Radio and Checkboxes buttons with a button background. In that case, you could create a custom solution for the buttons be replacing the Button and Checkbox/Radio backgrounds. In that case you will need to create custom skin where the sprites will contain your specific images.
Tutorial: How to create RadButton Custom Skin
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!