if (!context.selectedWidgets.contains(context.draggable)) {
context.dragController.toggleSelection(context.draggable);
}
// set context.mouseX/Y before startDragging() is called
Location location = new WidgetLocation(mouseDownWidget, null);
context.mouseX = mouseDownOffsetX + location.getLeft();
context.mouseY = mouseDownOffsetY + location.getTop();
// adjust (x,y) to be relative to capturingWidget at (0,0)
// so that context.desiredDraggableX/Y is valid
x += location.getLeft();
y += location.getTop();
startDragging();
} else {
// prevent IE image drag when drag sensitivity > 5
event.preventDefault();