I checked env in terminal emulator, the `GTK_IM_MODULE` was exported. 
Thanks a lot. The bug could be closed.

发件人: Yuuki Harano <masm+emacs@masm11.me>
发送时间: 2021年12月23日 8:23
收件人: LnJimMoen@outlook.com <LnJimMoen@outlook.com>
抄送: 52655@debbugs.gnu.org <52655@debbugs.gnu.org>; luangruo@yahoo.com <luangruo@yahoo.com>
主题: Re: 回复: bug#52655: 29.0.50 pgtk bug on X Window.
 

On Thu, 23 Dec 2021 16:07:53 +0000,
        Moen Jim <LnJimMoen@outlook.com> wrote:
> Thanks, the Environment "GTK_IM_MODULE" helps.

Good.

> pgtk maybe used the variable to confirm whether the current environment is CLI or GUI.

Gtk input methods behave differently by environment variables.

You seem to have misunderstood a Gtk input method behavior
as pgtk thinks it is running on CUI.

--
Yuuki Harano