想做出如下的界面:     ----------------------------------------|
     |                             |    B    |
     |                             |         |
     |              A              |         |
     |                             |_________|
     |                             |         |
     |                             |    C    |
     |_____________________________|_________|
     |                                       |
     |                  D                    |
     |_______________________________________|我使用的是CSplitterWnd类.可是,每次程序启动时窗口D总是满屏显示,别的窗口的大小都为0.