The return value is a handle to the foreground window. The foreground window can be NULL in certain circumstances, such as when a window is losing activation.
The return value is a handle to the foreground window. The foreground window can be NULL in certain circumstances, such as when a window is losing activation.
函数功能：该函数返回前台窗口（用户当前工作的窗口）。系统分配给产生前台窗口的线程一个稍高一点的优先级。