Pull Down Menu with Categories (getting large)

I am using the pulldown feature for the main menu on my site. Some of my categories has 10 items, and subcategories. If I have 5 or 6 pulldowns, my list in the menu setting page is starting to get large. It takes a bit of time to moving/floating my sub-categories onto the menu list. It would be nice to have a separate frame to scroll down the list.

Is there another way of setting up the menu so its easier? Maybe I don’t need to manually move each sub-category, and I can just choose the main category, and the sub-categories follow?