Description of problem:
Special keys like space, enter, back-spc not working on gtk4 app with hangul input.

Version-Release number of selected component (if applicable):
ibus-1.5.25-2.el9.x86_64
ibus-gtk4-1.5.25-2.el9.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Install ibus-gtk4 and gtk4-devel-tools
2. Add hangul input method
3. Open gtk4 app eg. gtk4-demo-application from gtk4-devel-tools
4. Enable hangul mode.
5. Input "rksi" and press the space key.

Actual results:
Space, backspace, enter key not working.
가야n

Expected results:
가야
Space, backspace, enter key should work.

Additional info: