最有可能，您要求在菜单项完全呈现之前输入坐标.尝试使用调度程序( GWT:计时器和调度程序类)等待直到菜单项完全呈现，然后在execute方法内询问坐标.

Most likely, you ask for the coordinates before the menu item is fully rendered. Try using a Scheduler (GWT: Timer and Scheduler Classes) to wait until the menu item is fully rendered and then ask for the coordinates inside the execute method.