I recently just starting playing around with TelerikTooltip for blazor.
Is it possible if I can add a custom tooltip to the items when mouseover?
Yes, it is possible to do that, by using Treeview Template and nested Tooltip in it, targeting the current template.
You can also find similar examples that show more details on using the tooltip and loading its content on demand in this sample project that shows how to use tooltips in the grid.
I'm providing you with an example in the attached file for the treeview, where you can take a look at how this is achieved. I hope this helps and if you have any other questions, let me know.
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