public override void ShowTooltipWindow (TextEditor editor, Control tipWindow, TooltipItem item, Gdk.ModifierType modifierState, int mouseX, int mouseY)
		{
			var location = editor.OffsetToLocation (item.Offset);
			var point = editor.LocationToPoint (location);
			int lineHeight = (int) editor.LineHeight;
			int y = (int)point.Y;

			// find the top of the line that the mouse is hovering over
			while (y + lineHeight < mouseY)
				y += lineHeight;

			var caret = new Gdk.Rectangle (mouseX, y, 1, lineHeight);
			tooltip = (DebugValueWindow)tipWindow;
			tooltip.ShowPopup (editor, caret, PopupPosition.TopLeft);
		}