You can save picture in progress to disk: click on Save and choose filename.
You can load it afterwards, just pick file near the Load button and press the Load button. Loaded picture will replace current picture state.
By clicking on picture squares you can paint them by selected color. Grey (color with question mark) is unknownje , White is empy, Black (and eventually other colors in multi-color griddlers)
is that square color, colors "+" and "-" are rotating colors on given square.
You can choose method of painting: individual squares or drawing a line with chosen color from clicked point in one of four directions to the nearest border