usually when opening a picture in NGG, it used to open in the foreground (with chosen effect, e.g. faded page in the background). When closing the picture, the page would be shown at the same position as before opening the picture.
However, when opening a picture, it opens as expected in the foreground, but at the same time, the article in the background jumps to the top of the page. This is annoying, since the user has to scroll down again to the part of the page he/she has been reading before opening the picture.
I am using NGG 1.5.5 with Avenue Dialogue Theme and WP 3.0 , but the bug has been there before upgrading to WP 3.0.