Basic snapped drawing.
rectangle drawing, fixed grid lines
3x3 dragging.
grid on separate layer.
Buildings as retained state.
Better context naming.
Building object.
Disable (break) PENCIL and RECT.
Draggable 3x3s.
Refactor, add require.js, multiple sizes of buildings, leave space for palette.
Color backgrounds.
Make Building a module.
Modulize Overlay and Designer. Drag correct shapes on placement.