关于菜单(50分)

为什么下面的函数不能用<br>for i := 0 to GetMenuItemCount(PopupMenu2.Handle) - 1 do<br>CheckMenuItem(PopupMenu2.Handle,0,MF_BYPOSITION or MF_Checked);<br><br>但是这个能用<br>hSysMenu := GetSystemMenu(Form1.Handle,False);<br>for i := 0 to GetMenuItemCount(hSysMenu) - 1 do<br>CheckMenuItem(hSysMenu,i,MF_BYPOSITION or MF_Checked);