Of course extension isn’t translated, but most of them aren’t 
.
But this isn’t my main problem here. I’m trying to make simple Paint-like program to get hang of this extension, but problem is that after drawing, things don’t stay on screen. Whatever I draw - rectangle, line or something else, it just flashes and is gone.
Yep, you have to force GD to redraw every line continuously. So, you must keep track of every lines drawn, and redraw them at every cycle, with a “For each object” event.
And this is just for lines. Imagine the headache for circles, curves, complex refill…
That’s what I was telling you in your previous post: make a drawing software out of GD will be extremely hard. It definetely isn’t suited for that kind of render. Not in my knowledge, anyway…