I have performed some local tests, base on the described scenario, but it seems that the cursor is correctly placed within the input of the control, like demonstrated in the video below:
In addition, in the attachment, you could find the sample page, which was used for the testing purpose. Could you let us know how your implementation differs from the demonstrated one? In addition, please specify the version of our controls that you are currently using and the browser under which the described problematic behavior occurs.
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