故障现象：
RemoteApp – 隐藏在主窗口后面的弹出窗口
原因 ：
Cause :
EVENT_SYSTEM_FOREGROUND comes too soon on the server. We end up sending the incorrect z-order to the client because in some scenarios the z-order calculation has not completed before we send it. A race condition exists in RemoteApp when a window is activated resulting in the activated window opening behind the previous foreground window. After the RemoteApp widow is activated, RdpShell.exe checks the server z-order before win32k.sys finishes computing the new z-order. When this condition occurs, Rdpshell.exe sends the wrong z-order instructions to mstsc.exe on the client. This fix introduces timer code to cause RdpShell.exe to wait for win32k.sys to finish computing the z-order before sending the new z-order to the client.
解决办法：
1. 将 HKEY_CURRENT_USER\Control Panel\Desktop 中的 ForegroundLockTimeout 的值更改为“0”
2. 注销/登录