bug#25214: #25214 26.0.50; Interacting with user from threads other than the primary

[Zhang Haijun]

> 在 2019年2月7日，上午9:39，张海君 <ccsmile2008@outlook.com> 写道：
> 
> 1. Create a fd to receive the input request event. This fd can only be 
> watched by main thread or a special keybord sheduler thread.

The fd may be a socket created by socketpair().