Thank you for your comment, Matthew. Launching the keyboard is not that easy task. Here is a thread I found on the matter: http://stackoverflow.com/questions/15554786/how-to-use-windows-on-screen-keyboard-in-c-sharp-winforms Still, the event would be nice addition.
Having the ability for your program to know whether or not a textbox has been selected by a mouse click or a touch screen tap, this could allow one to open the onscreen keyboard if tapped. This would be extremely useful to have the same functionality as the cell phone does when a textbox gets focus and the keyboard opens automatically. It would be even better if Telerik added a property to a textbox to automatically open the onscreen keyboard if tapped and another to close the keyboard on LostFocus... Very lazy of me I know :)