Thank you for contacting us.
The problem is that when you double-click the picker it starts an open animation upon the first click and attempts to close (open animation is still running) upon the second click. This causes a NullReferenceException to be thrown, which leaves the window in invalid state and that is why you see a blank (black) screen.
We have fixed the bug immediately and the fix will be available in our next CTP release.
I would like to thank you for your time and for reporting this bug. Your Telerik points are updated as a token of our gratitude.
All the best,
the Telerik team
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