Hello Cristian Blanc,
I'm assuming that you will know when window content is changed. When this happens you could call window.BringToFront method. This will bring the window on top. In order to make it flash you could edit the control template and add Storyboard in Focused VisualState that will change the window border two or three times (so that it looks like flashing).
Let us know if you need more information.
the Telerik team
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