It’s really all Bortels’ work. I made his font class draw into his image class and saved the results to project data files. The main advantage is that it’s much faster.
Woot! The lucious smell of work I was planning to do and someone did already 
I was hoping that would be faster - it only makes sense.
@ruilov: could you probably explain me how you did that? I fear I have not fully understood the concept of sprites. How do you handle the case of various background? It seems as if you do a default fill with white color, but later on this is not visible anymore. It’s a bit confusing to me. Your solution is very elegant, and I simply would learn more about that. Thanks! Would this be probably worth a tutorial?
Sprites are default transparent (0 alpha). So if you only set bits that are part of your drawing, the background shows thru.