Actually, the $find function takes the clientID of the control as parameter. That is why, you should not have problems using the suggested approach. However, there is a simpler way to get the currently visible tooltip:
| var controller = Telerik.Web.UI.RadToolTipController.getInstance();
| var tooltip = controller.get_ActiveToolTip();
| if(tooltip) tooltip.hide();
I have attached a simple test project based on the provided information to demonstrate how you can get the desired result.
I am not quite sure what the problem with the RadAjaxLoadingPanels is. In case you could provide us with a simple running project, demonstrating it, we will do our best to find what is causing it. However, in such cases as the one you describe, I believe the RadToolTipManager will help you get the desired result easier. Basically all you need to do is add the ClientIDs of the controls you need tooltipified to the TargetControls collection of the manager and use its AjaxUpdate event. The RadToolTipManager creates the tooltips on demand and places their content in UpdatePanels. Please refer to our online examples
for a basic overview of the functionality the RadToolTipManager provides.
Regarding your suggestion for Show and Hide server methods - I added it to our TODO list and updated your Telerik points.
the Telerik team