Tooltips
There are two ways to assign tooltips to RadSplitButton, namely setting the ToolTipText property of the RadSplitButtonElement, or as in most of the RadControls by using the ToolTipTextNeeded event of RadSplitButton. It is necessary the ShowItemToolTips property to be set to true which is the default value.
Setting the ToolTipText property
In order to assign different tooltips for the action part and the arrow button, you must specify the ToolTipText property of the RadSplitButtonElement.ActionButton or RadSplitButtonElement.ArrowButton element.
Setting tool tips in the ToolTipTextNeeded event
The ToolTipTextNeeded event has higher priority and overrides the tool tips set in the ToolTipText property.