fillCells method
Fills the buffer with the given fill
cell.
Implementation
void fillCells([Cell fill = Cell.empty, Rect? area]) {
area ??= this.area();
for (var y = area.top; y < area.bottom; y++) {
for (var x = area.left; x < area.right; x++) {
set(x, y, fill);
}
}
}