Show hidden files

[eskatos]

I have a use case where I need users to pick a hidden directory or a hidden file.
Would it be possible to add the ability to tell the file/folder picker to show hidden files?

[btzy]

I did a quick check - this is in principle possible for Windows, macOS, and Linux/GTK.

• On Windows, we want to set the FOS_FORCESHOWHIDDEN option
• On macOS, we want to set the showsHiddenFiles property
• On GTK, we want to call gtk_file_chooser_set_show_hidden

It doesn't seem possible to implement on Portals (the more "native" dialog on Linux).

Note that it's also possible for the user to change some setting in each OS that will allow them to view hidden files in all file dialogs.

[btzy]

I'm happy to accept a PR for this feature.