I am running Debian on an older system, and so am using MWM, as it is lightweight.

I am running Xorg at 1080x720 resolution. I'm not using multiple desktops. When I click "Maximize" on most applications, they correctly fill the screen. When I click "Maximize" on Mozilla Firefox though, it strangely maximizes to be almost 2000 pixels wide, and too tall, such that the right half and bottom half of Firefox are hidden.

Since this behavior only appears in Firefox, I assume Firefox has its own internal way to handle being maximized (though I am clicking the "Maximize" button on the window manager).

How can I correct this behavior, so Firefox correctly maximizes to fill the actual visible screen?


I determined Firefox is maximizing to 2048x1536, which is actually a common resolution. Somehow it is confused and thinks my computer is running at that large a resolution.

  • You could try a tool like wmctrl to resize the maximized window, then close firefox, and it might remember this value next time it is opened.
    – meuh
    Commented Jul 18, 2022 at 8:18

1 Answer 1


I found the solution is to add this line to ~/.Xdefaults:

Mwm*maximumMaximumSize: 1010x738

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