Frank, the name of the file is 100_1591 inside..Rust Bullit.JPG Even though this is a .jpg file, the gallery sees it as a .Rust Bullit.JPG and wont accept it. Just rename the picture and remove the .. between inside and Rust and it will work.
You can do it to an extent. Go to "Image Tools" and click "Edit Image". Go down to where it says Replace Image and click the Browse button. Then re upload the pic that you want in that position. You will then need to change the description and name to match, which can be done on the same page. Of course, you will loose the pic you had previously uploaded in that position, so you will need to reupload it in the spot that you want it. It would be nice if there was a "drag and drop" way to do it. Maybe an idea to throw out there to the software developers.
When uploading pictures to the forum, you can upload from your hard drive or directly from the Internet. I wish the gallery had that option, then it would be easier to move pictures from the forum to the gallery. Stefan