What's up with added EXIF data by gThumb ?

• Make a screen shot of your desktop
• Check with a viewer and see no EXIF data
• Load it in gThumb to use its crop feature, crop and save
• Check again with a viewer and see that gThumb added EXIF data including the gThumb version

In the mean time I've started to use other software to crop screen shots but I am still puzzled why gThumb always adds EXIF data ?