Howto create icons with Renew
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- Use drawing (e.g. add.draw) containing 16x16 rectangles of the size 20x20
- reduce size of drawing and export result to png
  - select all elements (Ctrl-A)
  - use sd command on prompt: sd 0.05 (i.e. reduce size by factor 20)
  - export to png (Ctrl-0)
