Sounds like the shiftable AL feature. Not quite sure which keys do it, since I've got extra keys on my keyboard, but I think it's \ and ^ (or something like that). Combined with "moveobjects on", you can place pictures and other shiftable furniture higher and lower than they normally go. Combined with "Boolprop snapobjectstogrid false", you can move the pictures freely around.
If you don't have AL, some of
these might help. I've got the AL shiftable ones, and I've not tried the BG compatible. If you have AL,
these might come in handy too.