BitBucket: https://bitbucket.org/namida42/neolemmixplayer/issues/12/have-a-move-to-closest-empty-space-option
It would be awesome to have a hotkey for "move the currently selected piece until it entirely occupies empty space". Shift + arrow key is a logical choice.
This would hugely cut down the time required for a fairly common task: making a wall out of copies of one piece.
Hotkey capability for "Duplicate Up/Down/Left/Right" has now been added and will be available in the next update (2.8.8). The default for each is Ctrl + Alt + (Arrow), since Shift + (Arrow) is already set to control the Piece Browser; users can of course reconfigure the keys as they wish.
Implemented in SuperLemmix Editor commit b4becbc, with a bugfix in commit 2606dfa to ensure that the default keys will be loaded into the Editor if the user hasn't yet set them up.