When an area of the image is selected, this option would reverse the selection and select everything that wasn't selected before. This combined with #92, #93, or #23 would allow for the common case of selecting an area in order to clear or fill the reverse area.
When an area of the image is selected, this option would reverse the selection and select everything that wasn't selected before. This combined with #92, #93, or #23 would allow for the common case of selecting an area in order to clear or fill the reverse area.