Vertices and edges are selected with the <1st> button, and their appearance changes upon selection. It is possible to select all of the objects in a rectangular region by clicking <1st> in an open area of the canvas, then dragging the mouse while holding the button. It is also possible to add to the selection with <Shift-1st>. SHIFT-1ST SHOULD BE A TOGGLE OPERATION, BUT IT IS NOT YET. NEEDS TO BE FIXED.