Plug not drawn and incorrectly positioned in xfce4-settings-manager

• Build https://gitlab.xfce.org/Tamaranch/xfce4-settings/-/tree/wlembed
• Run xfce4-settings-manager
• Click on appearance settings and return to the settings manager several times

The first time the appearance settings are not drawn, and from the second onwards they are drawn but incorrectly positioned.

Version: 0.0.0+281+gaee777c