hi I am seeing this problem just like this feedback posting http://feedback.telerik.com/Project/143/Feedback/Details/66990-on-smaller-resolution-the-datetimepickers-popup-is-showing-wrong
I can suggest as a workaround to modify the Template of the DateTimePicker in order to have a smaller drop down which will fit in smaller space.
I've created a sample project where the workaround is demonstrated (note that the project uses Implicit Styles).
Please test it on your side and let me know if it helps.
Regards,
Masha
Telerik
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