I examined the demo and the scenario you report. The behavior you describe is the expected one in this configuration and it comes from the fact that the dropdown is absolutely positioned and the last two items are outside the boundaries of the tooltip. That is why when you click on those items, the tooltip "understands" that there was a click outside it and this triggers it to close.
There are a few manners to resolve this and the easiest one is to simply make the dropdown smaller by setting its Height property to a proper value, e.g 80px and this is the way we will modify the demo on our side. Another solution is to use HideEvent="FromCode" or to check the mouse position in the OnClientBeforeHide and cancel the hide if the mouse is over the dropdown. However, since the purpose of the demo is to show LoadOnDemand functionality we prefer to have it as straightforward as possible and not to include such custom code there, furthermore none has complained about this so far. Thus, we will fix the demo by setting height to the dropdown, in case you want to implement one of the other manners and you encounter a problem, contact us again and we will do our best to help.
Thank you once again for your feedback, we highly appreciate it!
the Telerik team
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