Comment 15 for bug 1500282

I would like to adjust the patch to scale like the Windows code. I fail however to find any rounding there. I dug down to http://lxr.mozilla.org/mozilla-central/source/widget/windows/WinUtils.cpp#626 where GetDpiForMonitor is called and the value is return with no rounding applied. This is then passed through at http://lxr.mozilla.org/mozilla-central/source/widget/windows/nsWindow.cpp#1085 and used in http://lxr.mozilla.org/mozilla-central/source/widget/nsBaseWidget.cpp#565 .

Are there any test cases where odd devPixelsPerCSSPixel values lead to actually broken website display? I would like to test it.

As for GTK3 - I don't actually have a fully fledged GNOME system to test with, but can one set arbitrary values in the "normal user" control panel for the DPI/font scaling or does it have steps?

In any case, are we not in the same situation as in Windows, where the system deliveres a DPI value (however rounded/stepped it may be from the OS's point of view) and Firefox just uses this value to determine the defaultScale?