Hi Pilou, there isn't anything currently for this, but it is an interesting idea.

It sounds related to a "selection painter" tool. A "selection painter" would be a selection tool that you could activate and then click and drag and everything that your mouse encounters during the drag would become selected.

If this was available as a dedicated tool, then that tool could be used by pen-tablet users, and that would make it easier to have something like shift+drag be an alternative method to activate that tool.

But one thing that might be better is to have Shift+drag always activate the secondary selection mode, like for instance right now it is the rectangle area select. This is because sometimes you might want to use this type of selection in a crowded area where you don't have an empty spot to click on which is normally how it is triggered. Then there could be a setting for what the current secondary selection operation is, like rectangle, lasso, selection painter...

However it will be a while before I'll be able to experiment with actually adding any of this though.

- Michael