Hi , you can hold “Alt” key while clicking to to de-select face from multi-selected faces; Another trick is hold “Ctrl + Alt” to drag a selection box then let go of “Alt” key to de-select multiple faces from existing selection.
Technically unreal is also using “Shift” key for multi-select, and use “Ctrl” key for multi-select + toggle single select. I’ll add “Ctrl” as multi-select key too in next update. Thanks!
You mean you saw the blue selection highlight in game (PIE) mode? I haven’t noticed that myself but I’ll investigate.
In 4.15 and 4.16, you can go to Display Options - Face - Face Selected Color, set the color’s alpha to 0 to disable the selection highlight, but it turns out that’s broken in 4.17, I’ll dig more to see what has changed in 4.17. Thanks for bring that up!