drawn mask: cannot list shapes used

[darkbasic]

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

[dterrahe]

That drop down would list the shapes that exist, for example in other modules, that you could include in the mask for the current one. The shapes that are already used in the current module can be shown by clicking the right-most button in the row of shapes.

I don't know how well this is explained in the manual. You could suggest improvements there or improvements here that make the functionality more obvious.

[darkbasic]

You're right, maybe we could gray out the small arrow whenever there are no available shapes and so there is no drop down menu to be shown?

[dterrahe]

Sounds like a good idea; please feel free to submit a pr.