XnView Software

Editing an annotated image requires creating and editing it in a format that supports that, such as an Adobe image format, which XnView .software doesn't support to the required extent.

Supporting the .greenshot file format could be a solution. At least for viewing .greenshot files.
The .greenshot file format allows annotations to be edited.
Annotating an image is a great benefit - but annotating with the possibility of editing the annotations would be fantastic.
And Greenshot is open source, so it should be possible to find a way to use it. Could be a win-win situation for XnView & Greenshot.