Ok, this is the final.
The top table shows what icons are available at all in the stars_folder. It lists what icon membergroups and post groups uses, as well as telling you if a membergroup is missing an icon for a specefic theme.
If you look closely (friend), you can see that each theme can has its own icons

If a group is missing its icon in any theme, a red warning shows below the table with the name(s) of the groups and a lin to edit the groups.
You
delete an image by doubleclicking on it. It will only delete that image in that theme, not in all themes.
You
copy an image, by dragging it to the empty spot (Image Missing or N.A spots) and it will be copied there.
Both actions above, will ask you if you want to continue.
You
upload a new icon in the bottom. You can choose to upload the icon to all themes at once, or chose individual themes. You can rename the file in the upload process, so you don't have to rename it on your PC first. You can't convert it to another format, though!
By checking the "Overwrite existing file(s)", you will overwrite any present file that exists. If it isn't checked, it will only upload to themes where the image is not present.