I finally found the problem. My anti-virus software(360安全卫士) blocks emacs to emulate lwindow key. When emacs is trusted by anti-virus software, the problem is solved.


Thank you for all your help.



------------------ 原始邮件 ------------------
发件人:&nbsp;"Albert"<georgealbert@qq.com&gt;;
发送时间:&nbsp;2019年9月26日(星期四) 晚上9:40
收件人:&nbsp;"Eli Zaretskii"<eliz@gnu.org&gt;;"Juanma Barranquero"<lekktu@gmail.com&gt;;
抄送:&nbsp;"37495"<37495@debbugs.gnu.org&gt;;
主题:&nbsp;回复： bug#37495: 回复： bug#37495: 27.0.50; lwindow doesn't pass to system



Emacs 26.2/26.3/27.0.50 are downloaded from gnu website(http://ftp.gnu.org/gnu/emacs/windows/emacs-26/ and http://alpha.gnu.org/gnu/emacs/pretest/windows/emacs-27/).


I tried to comment code in w32fns.c to bypass lwindow to system, but failed without luck.





------------------ 原始邮件 ------------------
发件人:&nbsp;"Eli Zaretskii"<eliz@gnu.org&gt;;
发送时间:&nbsp;2019年9月26日(星期四) 晚上8:17
收件人:&nbsp;"Juanma Barranquero"<lekktu@gmail.com&gt;;
抄送:&nbsp;"Albert"<georgealbert@qq.com&gt;;"37495"<37495@debbugs.gnu.org&gt;;
主题:&nbsp;Re: bug#37495: 回复： bug#37495: 27.0.50; lwindow doesn't pass to system



&gt; From: Juanma Barranquero <lekktu@gmail.com&gt;
&gt; Date: Thu, 26 Sep 2019 13:45:03 +0200
&gt; Cc: Eli Zaretskii <eliz@gnu.org&gt;, 37495 <37495@debbugs.gnu.org&gt;
&gt; 
&gt; Why it didn't happen with 26.2, I have no idea.

Maybe Emacs 26.2 was downloaded from a different site, or it was a
different build?