Drag and Drop: Display items in groups horizontally.

I am attempting to display images in drag and drop groups horizontally or increase the width of the group dropping space. I have many pictures that need to be dropped into the groups (possibly 50 images across 5 groups) and the standard drag and drop function is cumbersome as images are dropped vertically in a column making it impossible to drag an image to a group further down the page. I can't stack images as all images need to be visible at once. Any ideas would be much appreciated.