[Feature suggestion] multi select with selection tools

In Piskel, the selection tools can only select one thing at a time. This makes it somewhat tedious if you're trying to move several groups of pixels that can't be moved with the lasso (for example, I was making a sprite in which I wanted to move 5 groups of pixels onto a different layer without moving the black outline around them (so the lasso wouldn't be useful, because I'd have so use it to select just the inside pixels). I think it would be a pretty simple feature to add the ability to hold shift or ctrl while selecting something to let you select multiple at once.