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Mixed DPI displays cause Firefox to open off screen

  • 8 replies
  • 1 has this problem
  • 6 views
  • Last reply by Michael

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I'm running Firefox 67.0.4 on Windows 10, and I have two monitors. One is set to HiDPI, the other is standard DPI. I've figured out that if I close Firefox and its last window is on the standard DPI display, the next time I open it it will straddle the two displays at a large scale. If I close the last window on my HiDPI display, it reopens normally on that display.

I've tried deleting the xulstore.json file but this doesn't fix this issue.

I'm running Firefox 67.0.4 on Windows 10, and I have two monitors. One is set to HiDPI, the other is standard DPI. I've figured out that if I close Firefox and its last window is on the standard DPI display, the next time I open it it will straddle the two displays at a large scale. If I close the last window on my HiDPI display, it reopens normally on that display. I've tried deleting the xulstore.json file but this doesn't fix this issue.

Chosen solution

All Replies (8)

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Here's an example of a window I closed on the low DPI display, and then where Firefox appears on next launch.

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And one more discovery: if the window on the low DPI display is small enough, it will appear in the same spot on next launch. E.g.:

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This might be a problem with hardware acceleration.

You can try to disable hardware acceleration in Firefox.

Close and restart Firefox after modifying the setting for changes to take effect.

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That doesn't seem to have made a difference unfortunately.

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Chosen Solution

It's probably a known issue, see https://bugzilla.mozilla.org/show_bug.cgi?id=1261441

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I think you're right.

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Note that the bug seems to be about 32-bit Firefox.

Did you close and rstart Firefox after modifying hardware acceleration?

Does resizing the Firefox window or using the system menu (Alt+space) work?

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Yes, I did close and restart Firefox after disabling hardware acceleration.

I can successfully resize the window after it launches partially offscreen, and like the bug report linked above notes, if I resize the window onto the second screen it snaps to a smaller size with the menubar visible. The issue is just with where the window appears on launch.