Left-click or left-click and drag to ?paint? cells with the current colour. Right-click to cross empty cells. Hold the Middle Mouse button to pan the view.
(1) Selects the ?cross? to mark empty cells.
(2-8) Switches to the corresponding colour.
(Z, X) Cycle through all available colours as well as the ?cross?.
(Spacebar) Pops up a small palette under your mouse cursor.
(Shift) Holding ?Shift? allows crossing cells without changing colours.
(Ctrl) Holding ?Ctrl? will allow you to click and drag the grid.
(W, A, S, D) Respectively moves the grid up, left, down and right.
(Q, E) Respectively Zoom Out and Zoom In.