Alt+click or double-click empty: new region + / − over region: change weight Ctrl+click region: toggle priority Shift+click region: toggle highlight Shift+Ctrl+click region: split in two Tab: toggle dim others
Right-click region: edit / delete
Voronoi: drag a region by its label Ctrl+Z: undo Ctrl+Shift+Z: redo Touch: double-tap to create, long-press to edit