Hello Telerik,
this thread seems to be very old, but we've recently discovered very similar problem on our side.
After window is opened with radopen, all tabindexes are reset in top window (the same behavior appears in IE7 and IE8). We are using dll version 2010.1.415.35.
The trick presented by Georgi worked, therefore I would like to know, whether it was actually fixed in Telerik libraries.
Kind regards,
Wiktor