As you can see, there is no leaves, and my leaves are svg costumes of sprites that I stamped. To save the svg costumes, I also tried to create a clone instead of stamping...
-> Is there anything I misunderstood ?
-> Is it a lot of work to include this export ? Because I would like to send nice svg flowers (obtained by exporting the stage in Snap!) for Christmas...
You need to use the "Pen down" and "Move <__> steps" (and "Turn" or "Point to") blocks only, because the SVG pentrails are created only this way (i.e. not by stamping or cloning costumes even if the costumes are themselves SVGs - it doesn't matter.).
So, you need to use a subroutine that will draw the leaves by using the "Pen down" and "Move" blocks.
At least that's my opinion. Maybe I am wrong, but this is how I understand the SVG pentrails creation process.