See http://www.telerik.com/community/forums/aspnet-ajax/tooltip/changing-targetcontrol-on-the-client.aspx It should be expected that this timeout around the public API is not needed and the problem is taken care of internally by the control.
When the page is in RTL mode and the manual close button of the RadToolTip is hovered it changes its position slightly.
The main wrapper of the tooltip is animated and the callout is positioned and shown after that. This makes it "pop" after the animation finishes. Disabling the shadow (EnableShadow=false) mitigates the effect somewhat. The callout can be positioned initially (if ShowCallout is not set to false) where it should be according to the Position property of the RadToolTip and its location can be updated at the end of the entire showing process again (as it is now).
The ContentScrolling property does not take effect under IE10. The end result is that the control behaves as if the property has its Default value (i.e. the browser will handle the overflow of the elements, which means large content will stretch the tooltips).
Many controls have items tooltip (RadComboBox, RadListBox, etc...) and every time is a pain to bind data in. You could implement support to "DataToolTipField" .....
When we have templates the generation of the clientIDs is dynamical. If some controls are removed and added back to the controls collection their clientIDs are changed. We can give a reference to the control in the Add method and onprerender the ToolTipManager could find their ClientIDs. E.g. the following demo: http://demos.telerik.com/aspnet-ajax/orgchart/examples/applicationscenarios/integrationwithradtooltip/defaultcs.aspx. is not working when we have DrillDown.