Ability to check mark selected/all/none rows

[gingerbeardman]

Is your feature request related to a problem? Please describe.

• The fist time I add games to mey SD I have to click each game, hundreds of them

Describe the solution you'd like

1. select rows
2. click to check all selected rows, maybe with use of modifier key?

Also a way to check all rows, none rows, invert selection might be useful.

Describe alternatives you've considered

• ticking each box individually