Some toolbar commands have no corresponding icon. For the new Mezich-48 skin I created four icons:
The sources came from www.clker.com/. If the SVG worked I converted it to PNG with rsvg-convert -o image.png image,svg. For the reload image I downloaded the PNG and converted it to a square image with the XnView "canvas size" function. After that I used ImageWorsener to get a 48×48 PNG with option -noopt all to preserve RGBA with transparency. Finally ffmpeg converted the small PNGs to ordinary ICO files, and XnView allowed me to use these icons for the toolbar buttons. Icons, PNGs, and SVGs attached as ZIP.
Still missing (for my purposes) are four icons for Sequence convert, Multi-page file, Strip of images, and Copy image data.