how about an option to invert the selection?
i dont get the need for this. When multiple files are selected you can already right click/ Tick (or Untick) Selection
I was just thinking that sometimes, if you only want a few selections ticked, it would be easier to untick those and then invert the selection.
I suppose, looking at it another way, you could just
right-click>untick the entire selection and then just tick the items you need.
same number of steps - same outcome
just a different mind-set needed
either way, it would be something that probably wouldn't be needed very often.