If even setting a non-existing skin name does not result in a server error then it seems that you have this property set on a more global level - in the web.config, in the code-behind or in a Theme. Please make sure this not the case in your project. You can examine the following help article for some hints on the different ways to do so: http://www.telerik.com/help/aspnet-ajax/introduction-skin-registration.html
If you disable the embedded skins and the embedded basestylesheet, yet you register the base stylesheet manually you would get a basics defined there, but hardly any colors/borders/etc. I'd advise that you follow the steps from the following help article to create your custom skin exactly: http://www.telerik.com/help/aspnet-ajax/tooltip-appearance-creating-custom-skin.html
. Once you are able to get this custom skin running you should be able to easily replace the skin-specific file with the one you get from the VSB (create them with the same name, of course).
The easiest way to determine if the issue stems from a setting in the current project is to create a new one and only place your custom skin there with a simple test page. If it works correctly there you would need to examine your project for a setting like this.
As for the close button - the ManualClose property is obsolete. You should use the HideEvent
property and set it to ManualClose
. On the matter of the RadToolTip being different from the RadToolTipManager - indeed there is a difference as the manager offers richer functionality in many areas, yet is more complex to use, as its purpose is to cover complex scenarios. On the difference between the two you can examine this online demo
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