Describe the bug
Hey! I'd really love to give Synfig a shot, but it seems to be unresponsive to the point of being completely unusable on my machine. The issues are difficult to describe, so I've attached a video:

Essentially,

• Menus are unresponsive
• Nothing can be selected from the file browser
• I'm unable to pan or zoom on the canvas
• Synfig misbehaves when its window gets resized
• The shadow on Synfig's window appears to be duplicating itself

To Reproduce
Steps to reproduce the behavior:

1. Launch the AppImage version of Synfig on a machine running Fedora Workstation 43.
2. Try panning and zooming on the canvas using middle mouse click and the scroll wheel.
3. Go through the menus in the menubar.
4. Restore the Synfig window down from being in full-screen.

Expected behavior
The application is responsive, and the user is able to use the application like any other.

System information:

• Linux distro: Fedora Workstation
• OS version: 43
• Package: AppImage (the RPM and Flatpak from Flathub don't run)
• Synfig version: 1.5.3