Problem statement
I'm not sure what's actually Spine uses to display the native file dialog on Ubuntu, but it's very old and quite stressfull to use. It's not user friendly and sometimes it doesn't show at all! It goes behind the main window and it's not focusable anymore. Sometimes I'm forced to kill the process because unable to close the editor in any other way (close button become unresponsive while waiting the file selection) [losing works sometime].
A pretty well alternative could be the use of the tinyfd library https://sourceforge.net/projects/tinyfiledialogs/ (available in LWJGL3 bindings). I've used in my libGDX app for long time and always worked well on Windows, macOS and major Linux distributions.
Current file dialog
TinyFileDialog
The dialog allow to navigate quickly in the file system, also access to external volume storage and integrates much better with the system in general. Moreover it doesn't lose it focus while switching windows.
I know that Linux users are pretty few and it's more or less fine as is, but I'd really appreciate if you could consider to switch at least on this platform the file dialog and let our life a little easier 😄
Editor information
Spine 4.2.33
