application display overflow to outside its window

[guyuming76]

when i debug my custom rfm application with gdb in dwl, i see this problem:

1. there are three windows on screen, that is, there are two window on the right stack area

2, when i press MOD+enter to move the rfm window to upper right, it overlaps the other window on the stack area. How can it be? I think that no matter what the application render, it should be only inside it's window.

rfm is a gtk application, i see message in its stdout:
Gdk-Message: 12:18:14.313: Error flushing display: Broken pipe

[sevz17]

This will probably will fixed until wlroots-0.17, see https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4131