Select all / Deselect all functionality in the filter by value.
Very usefull when we have long list of values.
Handsontable PRO filter
I think you’re reading in our minds @jacques.bourquin 
We were talking about this feature few days ago and we will definitely start to work on this one.
Currently we’re refactoring formulas and crafting new feature - nestedRows but the select/deselect all option should be ready till we reach July.
It’s not there yet but you can track our Roadmap for updates: https://trello.com/b/PztR4hpj/handsontable-roadmap-2016-login-to-vote-for-features
Good news thanks !