[Bug Report] Windows auto-hide taskbar fails to draw the bottom 1px over maximized Firefox

Windows auto-hide taskbar fails to draw the bottom 1px over maximized (not full-screen) Firefox (quantum) in the built-in Administrator account and on the primary (first) display.
This quite annoying bug is present since Windows 10 (at least) + Firefox quantum (i.e. Version 57+, 2017) and now, finally, I specified the condition.

Conditions for reproducing this bug

1. Enable the built-in Administrator account and login it. ("net user administrator /active:yes")
2. Set taskbar auto-hide via "Taskbar behaviours" (in Settings).
3. Install the current Firefox, open and maximize (not full-screen) it on the primary (first) display. (In the multiple-display environment, auto-hide works fine on the displays except for the first one.)
4. Auto-hide taskbar fails to draw the bottom 1px over maximized Firefox, and the taskbar does not come up even if put the pointer to the bottom.