I am not quite sure what exact element of the RadDatePicker you want to tooltipify and in what manner - there are many ways to tooltipify an element either with a separate RadToolTip or RadToolTipManager. For your convenience I prepared a sample demo which shows the very basic and most simple scenario of tooltipifing the whole RadDatePicker.
In case this is not what you meant, please provide more detailed information about your setup and some code or best - open a new support ticket and send me a sample reproduction demo along with detailed reproduction steps and explanations of the actual and the desired behavior.
Sincerely yours,
Svetlina
the Telerik team
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