Solve newwin fingerprinting + issues

fix newwin (& it's inner measurement entropy) with and w/out LBing

• not letterboxing
• not betterboxing
• not UI/UX or toggling UI (e.g. #41564, #42020)
• not zooming/resizing/maximizing/full-screening after newwin (e.g #16456 (closed), #40858 (closed), #20129 (closed), #20941 (closed), #41585 (closed), #41723)
• ignoring #27083 (closed) as I think #30945 is the answer
• i.e not inner window changes

cc: @ma1 @pierov @richard