The biggest problem with GNOME right now is Gtk3 and gtkfilechooserwidget.c. It is so spaghetti and so many things rely on it that no one at GNOME is willing to work on it for fear of breaking something. And for the same reason they won't accept drive-by patches. It is, effectively, frozen broken, and has been for many years. This applies to any attempt to add thumbnails to the file chooser but there are far worse, actual bugs, beyond the lack of thumbnails.
As of right now if you File->Open in any program using modern Gtk3 and try to paste a file path in you'll get an error instead of pasting your filepath in a text field to open, "The folder contents could not be displayed\nOperation not supported" http://erewhon.superkuh.com/gtkfilechooserwidget-paste-fail....
It's unfixable behavior because the GNOME devs stopped respecting their own gsettings, org.gtk.Settings.FileChooser location-mode, to FORCE the path-bar experience on everyone. Because no one needs to type file paths, apparently. So why bother respecting the settings for path-bar or filename-entry? Their demographic doesn't care. Unfortunately gtk3 is used by far more than GNOME's demographic.
They have fixed this bug in gtk4, for all the good that does.
As of right now if you File->Open in any program using modern Gtk3 and try to paste a file path in you'll get an error instead of pasting your filepath in a text field to open, "The folder contents could not be displayed\nOperation not supported" http://erewhon.superkuh.com/gtkfilechooserwidget-paste-fail....
It's unfixable behavior because the GNOME devs stopped respecting their own gsettings, org.gtk.Settings.FileChooser location-mode, to FORCE the path-bar experience on everyone. Because no one needs to type file paths, apparently. So why bother respecting the settings for path-bar or filename-entry? Their demographic doesn't care. Unfortunately gtk3 is used by far more than GNOME's demographic.
They have fixed this bug in gtk4, for all the good that does.