When the mouse leaves a scroll list, don't leave the mouse-over highlight shown

indra/llui/llscrolllistctrl.cpp

@@ -1922,6 +1922,11 @@ BOOL LLScrollListCtrl::handleHover(S32 x,S32 y,MASK mask)
 	return handled;
 }
 
+void LLScrollListCtrl::onMouseLeave(S32 x, S32 y, MASK mask)
+{
+	// clear mouse highlight
+	mouseOverHighlightNthItem(-1);
+}
 
 BOOL LLScrollListCtrl::handleKeyHere(KEY key,MASK mask )
 {

indra/llui/llscrolllistctrl.h

@@ -261,6 +261,7 @@ public:
 	/*virtual*/ void	setFocus( BOOL b );
 	/*virtual*/ void	onFocusReceived();
 	/*virtual*/ void	onFocusLost();
+	/*virtual*/ void	onMouseLeave(S32 x, S32 y, MASK mask);
 	/*virtual*/ void	reshape(S32 width, S32 height, BOOL called_from_parent = TRUE);
 
 	virtual BOOL	isDirty() const;