Win7 should require DWM (Aero) only for partial present (instead of blocking WebRender completely) and Firefox graphics should be reinitialized when the user changes the Windows theme: When switching from Aero to non-Aero, wrong window buttons are shown and the corner looks incorrectly cut out until you restart Firefox.
Bug 1637497 Comment 20 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Firefox on Win7 should require DWM (Aero) only for partial present (instead of blocking WebRender completely) and Firefox graphics should be reinitialized when the user changes the Windows theme: When switching from Aero to non-Aero, wrong window buttons are shown and the corner looks incorrectly cut out until you restart Firefox.