Hello Amir,
Unfortunately, the manual setting of
ZIndex is a problem introduced by the latest plug-in version of Silverlight. We have reported this issue to Microsoft and we hope that they will consider changing this behavior, because it's quite inconvinient not to use this property. That is why, RadWindow currently doesn't support the TopMost functionality. Moreover, the ZIndex is controlled by the framework, and the only way to have a menu over our RadWindow control is to open the menu after you have opened the RadWindow control. In this way the ZIndex of the most recent control will have the highest ZIndex order.
Regards,
Hristo Borisov
the Telerik team
Check out
Telerik Trainer, the state of the art learning tool for Telerik products.