drawn mask: cannot list shapes used

Describe the bug/issue
Whenever you create a drawn mask from any module (in this example filmic rgb) if you click on the small arrow near the used shapes which is supposed to list them it doesn't work.

To Reproduce

1. Go to 'filmic rgb' module
2. Click on 'drawn mask'
3. Add some shapes
4. Click on the little arrow near the used shapes

Expected behavior
It should list the used shapes.

Screencast
https://www.youtube.com/watch?v=ENbDJjphZtY

Which commit introduced the error
I have no idea if it used to work or not.

Platform

• darktable version : 4.1.0+1086~ge56f3d964-dirty
• OS : Linux - kernel 6.0.9
• Linux - Distro : Gentoo ppc64le (4K page size)
• Memory : 64 GB
• Graphics card : AMD RX 570
• Graphics driver : mesa git karolherbst/mesa:rusticl/si
• OpenCL installed : rusticl
• OpenCL activated : no
• Xorg : Wayland
• Desktop : Gnome 43
• GTK+ : 3.24.34
• gcc : 11.3.0
• cflags : -O2 -pipe -mcpu=power9 -mtune=power9
• CMAKE_BUILD_TYPE : RELWITHDEBINFO

Additional context

Reproduce the issue in the filmic rgb module by creating a drawn mask with several shapes and clicking the arrow beside the used-shapes control. Trace the drawn-mask UI handling from that control; done means the arrow lists the shapes currently used by the mask.