Hello Mischa Müller,
Sorry for the late response.
In order to hide the RadCalendar you should edit the control template and remove the calendar (and probably you will want to remove the toggle button).
Calling focus on the date picker do not call focus to the input box. But using Tab key should allow you to focus the input box.
This is good suggestion. I've added it to the features list but I can't promise that it will be implemented for the Q1 release.
Thanks for your suggestion. I have updated your telerik points.
the Telerik team
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