When opening a file with long filename, the window width explodes

[nekohayo]

Originally filed at flathub/com.github.muriloventuroso.pdftricks#15

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As observed with the latest flatpak version from Flathub, running on GNOME 50.1 (Wayland) on Fedora 44:

This is strange because it seems like the file picker button does have ellipsization at the end ("…") but it clearly is not stopping the window width from being expanded whenever you have a long filename...