Bug 159600 [Viewers] Tooltips not working on TreeViewer
TooltipSupport does not map receiver-relative coordinates to display-relative coordinates => TreeViewer#getItem(int x, int y) returns wrong item.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ToolTipSupport.java
Image img =  labelProvider.getToolTipImage(element);
				
				if( img != null) {
					label.setImage(img);
				}
				
				Color color = labelProvider.getToolTipForegroundColor(element);
				if( color == null ) {
					color = viewer.getControl().getDisplay().getSystemColor(SWT.COLOR_INFO_FOREGROUND);
				}
				label.setForeground(color);
				
				color = labelProvider.getToolTipBackgroundColor(element);
				if( color == null ) {
					color = viewer.getControl().getDisplay().getSystemColor(SWT.COLOR_INFO_BACKGROUND);
				}
				label.setBackground(color);
				
				Font font = labelProvider.getToolTipFont(element);
				
				if( font != null ) {
					label.setFont(font);
				}
				
				Point pt = viewer.getControl().toDisplay(p);
				Point shift = labelProvider.getToolTipShift(element);
				
				if( shift == null ) {
					pt.x += DEFAULT_SHIFT_X;