The X button used to appear when you set the RadToolTip's ManualClose property to true. However, now the ManualClose and the Sticky properties are obsolete - they still can be used but we do not recommend this because problems may occur especially when using both of them in a combination because this scenario is not a valid one. I strongly recommend to use the new property which replaces them - the HideEvent property which is demonstrated here. Please, replace all the occurrences of the obsolete properties with the new ones and test again.
This being said, if the replacement of the old properties does not help and you are not using a skin different than the ones listed in the skinning demo, I will need to examine your code - please send me a sample, fully runnable reproduction demo along with reproduction instructions.
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