Hello Prayag,
You are updating the tooltip's content via AJAX, so the tooltip does not know the size of the content it is going to have to display and it renders with the default size (75 pixels). This is the reason these dimensions should be reset when the information is received from the AJAX update so that the tooltip resizes its wrapper properly. Here is a JavaScript function that does exactly that:
It should be attached to the
OnClientResponseEnd event of the RadToolTipManager.
I hope this helps. Please let me know if the above solution works for you. If you are still experiencing this behavior after applying this fix please send us a simple runnable project that displays the issue so we can debug it locally and pinpoint the cause.
Greetings,
Marin
the Telerik team