Try using a different package like the official Mozilla build. If you are using snap or flatpak, make sure you have the relevant portal packages installed:

xdg-desktop-portal
xdg-desktop-portal-gtk
xdg-desktop-portal-gnome
xdg-desktop-portal-kde

On MS Windows, there is a "control menu" you can invoke by pressing Alt+Spacebar. This menu has a "Size" option. Do you have anything like that on Linux?

The way that works is:

• Alt+Spacebar
• Click Size (or press the S hotkey)
• Press the right arrow key once to select the right border
• Hold down the left arrow key to move the right border leftwards
• Press Enter to save the new dimension
• Repeat as needed with other borders

Try to rename/remove xulstore.json in the Firefox profile folder with Firefox closed.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

On MS Windows, there is a "control menu" you can invoke by pressing Alt+Spacebar. This menu…

Thanks. I'd already found that hint but was unable to find any trigger mechanism for said menu on Linux, if it even exists there.

Try using a different package like the official Mozilla build…

I am using an official build, and am not in a namepace based container (or any kind of container) so was not invoking a portal.

Symptom has returned. Removing xulstore.json has no effect this time.

This is in firefox 120.0.1

unable to find any trigger mechanism for said menu on Linux

It depends on your Window Manager (WM) or Desktop Environment (DE). Ubuntu 23.10 (GNOME) uses Alt+Spacebar which allows resizing the file picker window with the keyboard.

I am able to resize other windows but not this one (it used to be resizable in older firefox versions but at some point stopped responding to the resize mechanism)

It works for me with version 120.0.1 snap/flatpak/apt packages on GNOME 45. What is your WM/DE?

Try installing the flatpak version.

I am using fvwm inside xfce (and yes, I realise this is niche but apart from this issue it works the way I like).

The flatpak version does allow me to resize the file picker via my normal resize mechanism (and also isn't far too large to start with). There's still no ctrl-space menu, but the wm can resize the window.

There's still no ctrl-space menu, but the wm can resize the window.

Issue resolved?

Not really. The non-flatpak versions of firefox 120.0.1 are making the filepicker too large, in a way that can't be overridden or fixed, which is kind of annoying.

The picker is slightly too large on one of my machines (where it used to be fine) and about 3x the size of my display on another (which was fixed by removing xulstore.json but is not fixed by that anymore). So the bug appears to be getting worse.

Also the xulstore doesn't _have_ an entry for the file picker, so I'm curious as to why removing it _ever_ fixed this bug.

Let me install XFCE and kick it around, but in KDE Window Manager there is a setting that can set the size for all windows. Once you get the File Picker window, you can then delete the rule for all windows. Let me know if XFCE has this option.

There's probably something similar. I'm packing up my office now, going to be travelling for a couple of days. I'll check back in after the w/e when I've had time to try that.

ersatzmaus said

unable to find any trigger mechanism for said menu on Linux

It depends on your Window Manager (WM) or Desktop Environment (DE). Ubuntu 23.10 (GNOME) uses Alt+Spacebar which allows resizing the file picker window with the keyboard.

In XFCE (very painful experience ;-/)the Alt+Spacebar brings up the menu to move or resize. see screenshot

Also, while in XFCE, I did experience the file picker going full screens for some strange reason.

Regarding ALt+Space - I'm not using the xfce wm, I'm using FVWM - which does have a mechanism for resizing arbitrary windows even if they don't have decorations, which works on the flatpak file picker window, and on arbitrary windows from firefox or other applications, but specifically _not_ on the file picker from non-flatpak firefox.