Fedora 33 firefox-88.0.1-1.fc33.x86_64 Window manager is fvwm.

[~]$ xrandr Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 8192 x 8192 LVDS-1 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 382mm x 215mm 1600x900 60.01*+ 59.99 59.94 59.95 59.82 ... VGA-1 connected 1920x1080+1600+0 (normal left inverted right x axis y axis) 509mm x 286mm 1920x1080 60.00*+ ...

xrandr --output VGA-1 --primary xrandr Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 8192 x 8192 LVDS-1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 382mm x 215mm 1600x900 60.01*+ 59.99 59.94 59.95 59.82 ... VGA-1 connected primary 1920x1080+1600+0 (normal left inverted right x axis y axis) 509mm x 286mm 1920x1080 60.00*+ ...

palemoon browser stays on screen where is launched. New window opens on the same screen.

firefox always opens on LVDS-1, even when is launched on VGA-1. After moving the window to VGA-1, new window again appears on LVDS-1. No matter if the screen is primary or not.

Any clue?

TIA, Bob