Image capture problem (bug?)

I find a problem when I use Image capture. After using it twice in a score (i.e. saving two images) when I move the selected area to the next thing I want to capture it suddenly moves out of sight. If I go there and try moving it, it jumps away again. Even if I toggle "Image capture" and try again it keeps doing the same thing, and I just can restart the program, capture twice, restart...
This is quite unconvenient when you have to do it many times. I wonder if it is a bug that can be solved.