Bugzilla

(In reply to Glenn Watson [:gw] from comment #9)
> When you say "default sized window" above, could you confirm the monitor resolution and what that window size / position is? Maybe I'm failing to repro due to something different there.

I don't think the window *position* matters, based on my testing. (Wayland often puts the window in a semi-random spot, and that doesn't seem to matter on my end.)

I've got my (widescreen) monitor resolution set to 3440x1440 (with 125% scale as noted above).

As to my viewport size, there are two different scenarios that reliably reproduce the issue for me, with mozregression and 125% desktop scaling and 150% browser scaling:
(1) Running with `security.sandbox.content.level:0 ` (which I do sometimes for mozregression purposes to avoid crashes in old builds) -- this adds a warning-toolbar which steals a bit of space from the content viewport.  That toolbar appears to be what was responsible for me being able to repro without opening devtools in comment 5 first sentence.  This gives me a viewport of size `853.333px x 467.2px` (based on hovering the `html` element in DevTools inspector).

(2) Running without that^ about:config pref, and just opening devtools with F12.  It looks like this gives me a viewport of size `853.333px x 599.467px` (based on hovering the `html` element, in DevTools running-in-a-separate-window rather than in a footer-bar).

Note that the viewport sizes here are in **CSS pixels**, which are wider-than-they-might-otherwise-be because of my 150% full-page-zoom (and of course the 125% desktop zoom).

(In reply to Glenn Watson [:gw] from comment #9)
> When you say "default sized window" above, could you confirm the monitor resolution and what that window size / position is? Maybe I'm failing to repro due to something different there.

I don't think the window *position* matters, based on my testing. (Wayland often puts the window in a semi-random spot, and that doesn't seem to matter on my end.)

I've got my (widescreen) monitor resolution set to 3440x1440 (with 125% scale as noted above).

As to my viewport size, there are two different scenarios that reliably reproduce the issue for me, with mozregression and 125% desktop scaling and 150% browser scaling:
(1) Running with `security.sandbox.content.level:0 ` (which I do sometimes for mozregression purposes to avoid crashes in old builds) -- this adds a warning-toolbar which steals a bit of space from the content viewport.  That toolbar appears to be what was responsible for me being able to repro without opening devtools in comment 5 first sentence.  It looks like this gives me a viewport of size `853.333px x 599.467px` (based on hovering the `html` element, in DevTools running-in-a-separate-window rather than in a footer-bar).

(2) Running without that^ about:config pref, and just opening devtools with F12.  This gives me a viewport of size `853.333px x 467.2px` (based on hovering the `html` element in DevTools inspector).

Note that the viewport sizes here are in **CSS pixels**, which are wider-than-they-might-otherwise-be because of my 150% full-page-zoom (and of course the 125% desktop zoom).