Hi

I do not know that window manager (I use Xfce), but is there a context menu item for open apps in the toolbar that allows you to "unmaximise" an open app?

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

Hi I do not know that window manager (I use Xfce), but is there a context menu item for open apps in the toolbar that allows you to "unmaximise" an open app?

Yes, there is such button, it's located on the toolbar on the right side. But I have to drag the whole window to the left side to get that button. I can also press Alt+F5 to bring the size to the original one, but I'd like the maximize to work as it worked before Firefox 73 and as anyone would expect -- just maximize to the allowed screen. Just trying to figure out if I'm doing something wrong or it's a bug in Firefox.

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

I'm sorry I forgot to mention that I tried it with my profile completely deleted and that did not help.

Did you also check your monitor settings as well to insure they were adjusted correctly and also is the driver the correct driver and set to the right resolution? Coming from Windows that's what I would look at as well.

I'm not sure how that would affect it. Please note that any version before Firefox 73 works as expected, but anything starting with Firefox 73 and forward does not work properly. If I would have incorrect driver, then all versions would not work.

Does Full Screen mode behave the same way or does that give a normal window size ?

I assume that you did try a new profile since you mentioned you did delete the profile?

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

You can try Firefox from the official Mozilla server if you currently use a version from the repositories of your Linux distribution or a snap/flatpack version to see if it behaves differently.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

See also:

• https://www.quirksmode.org/m/tests/widthtest.html

Does Full Screen mode behave the same way or does that give a normal window size ?

Yes, it does the same thing when in the Full Screen mode. I experience the same exact thing. Any version up to Firefox 72 including work fine, but Firefox 73 and newer extend behind the screen's resolution.

I assume that you did try a new profile since you mentioned you did delete the profile?

Yes, as I responded to you earlier, I tried to delete all my profiles and start from scratch. The same issue. I don't have any 3rd party extensions or any settings. Basically, a brand new installation behaves this way.

See also:

• https://www.quirksmode.org/m/tests/widthtest.html

That's an interesting test. Here is what I get using Firefox 73 and higher (unexpected behavior):

This test has no <meta viewport> tag. Iteration 1 screen.width/height = 1400 / 800 documentElement.offset = 2800 / 480 documentElement.client = 2800 / 1526 window.innerWidth/Height = 2800 / 1526 window.devicePixelRatio = 1 window.page = 0 / 0

And this is what I see in Firefox 72.0.2 (the latest "good" version):

This test has no <meta viewport> tag. Iteration 1 screen.width/height = 1400 / 800 documentElement.offset = 1386 / 499 documentElement.client = 1386 / 695 window.innerWidth/Height = 1386 / 695 window.devicePixelRatio = 1 window.page = 0 / 0

See also:

• https://www.quirksmode.org/m/tests/widthtest.html

That's an interesting test. Here is what I get using Firefox 73 and higher (unexpected behavior):

This test has no <meta viewport> tag. Iteration 1 screen.width/height = 1400 / 800 documentElement.offset = 2800 / 480 documentElement.client = 2800 / 1526 window.innerWidth/Height = 2800 / 1526 window.devicePixelRatio = 1 window.page = 0 / 0

And this is what I see in Firefox 72.0.2 (the latest "good" version):

This test has no <meta viewport> tag. Iteration 1 screen.width/height = 1400 / 800 documentElement.offset = 1386 / 499 documentElement.client = 1386 / 695 window.innerWidth/Height = 1386 / 695 window.devicePixelRatio = 1 window.page = 0 / 0

I tried a clean install of Debian on another device with a completely different set of hardware and configuration. Including a different monitor/resolution. The issue appears when I use MWM only. When I tried GNOME and Xfce, it works as expected. So it seems like some change was introduced in Firefox 73 which caused an issue when it's running under MWM.

FYI, I would assume there is nothing much can be done on my side to mitigate the issue. So I went ahead and opened a bug report on this: https://bugzilla.mozilla.org/show_bug.cgi?id=1808992

Right-click on the desktop and select Properties > Settings tab. Move the slider to select a screen resolution of at least 1024 by 768 pixels.

Regards, Will

Right-click on the desktop and select Properties > Settings tab. Move the slider to select a screen resolution of at least 1024 by 768 pixels. Regards, Will

That is for Windows when the OP is clearly using Linux.

Right-click on the desktop and select Properties > Settings tab. Move the slider to select a screen resolution of at least 1024 by 768 pixels.

Thanks for the suggestion. As I mentioned before, my monitor is set to 1920x1200. I don't see how setting a lower resolution would help in this case. The browser starts at smaller window size, but gets extended way over my monitor's resolution when maximized.