Suggestion: "Slice"
Before executing this operation, the user creates a selection area that goes from one edge (horizontal or vertical) to the opposite edge. When the user clicks on "slice," what happens is:
a. the selected area is deleted
b. the remaining areas are moved "together"
c. the image is resized so that all the deleted area is gone
For example, let's say I have an image that is 1000 pixels wide by 500 pixels high.
1. I select an area in the middle of the image that is 200 pixels high by (of course) 1000 pixels wide
2. I hit "slice"
3. XnView produces a new image that is 300 pixels high (500 original minus 200 selection) by 1000 pixels wide, and from which the selected area is missing.