Bugzilla

Here is a minimal testcase demonstrating the bug: https://theres-waldo.github.io/mozilla-testcases/bug1889017.html

The STR for it is:

  1. Load the testcase
  2. Orient the tablet in landscape mode
  3. Request desktop site
  4. Tap the yellow element to enter fullscreen mode
  5. Try to tap the green element to exit fullscreen mode

The bug also reproduces on a phone with the pref `browser.viewport.desktopWidth` set to a sufficiently small value. (It needs to be smaller than the width of the screen in landscape mode divided by the device scale; for example, on a phone with a screen height of 1920px and a device scale of 3.0, the pref value needs to be smaller than 1920 / 3 = 640.)

Here is a minimal testcase demonstrating the bug: https://theres-waldo.github.io/mozilla-testcases/bug1889017.html

The STR for it is:

  1. Load the testcase
  2. Orient the tablet in landscape mode
  3. Request desktop site
  4. Tap the yellow element to enter fullscreen mode
  5. Try to tap the green element to exit fullscreen mode

The bug also reproduces on a phone with the pref `browser.viewport.desktopWidth` set to a sufficiently small value. (It needs to be smaller than the width of the screen in landscape mode divided by the device scale; for example, on a phone with a screen height of 1920px and a device scale of 3.0, the pref value needs to be smaller than 1920 / 3 = 640.)

It does not reproduce 100% of the time but it does fairly often.