Equip a chalk to activate Chalk++

Press Y cycle modes, hold down <shift> + Y to cycle backwards

You can hold down <SHIFT> while using checkerboard pattern to offset the cells targeted by -- It's hard to explain but you'll see what I mean.

you can mask while using dithering brushes, by holding <CTRL>

In addition to alpha masking you can select a specific masking color by holding <ALT> and scrolling your mouse wheel-- any chalk that you draw outside of this color will be discarded

While holding down <ALT> click on a canvas cell to select the color of the cell as your masking color

To fill, equip the chalk/color you'd like to apply, select fill mode from the menu, and click on the color/area you wish to fill