flatpak built with gnome platform 47 doesn't change cursor in drawing mode

[sudopluto]

If you'd like to put out an incentive for fixing this bug, you can do so at https://issuehunt.io/r/bk138/gromit-mpx

Describe the bug

When in drawing mode, the cursor doesnt change to show that the pen / eraser is active.

To Reproduce

build flatpak with gnome platform v47
run application
switch to drawing mode and observe the cursor not changing

Expected Behavior
the cursor changes to match pen / eraser state

Screenshots
can send video if helpful

Environment (please complete the following information):

• Gromit-MPX version: devel / head
• Flatpak or Distribution-package or Built-from-source: flatpak built locally
• OS and version: arch linux
• Desktop Environment and version: gnome 47
• X11 or Wayland session: wayland

[bk138]

@sudopluto is that maybe a dupe of #210, can you pls check?