I created a custom theme and ran into a couple of issues.
If you don't allow the delay for the fly-out menu to disappear to be adjusted, you may as well not allow the "space" around the menu to be adjusted. I wanted a gap between the menu item and the fly-out menu, but even a 2px gap requires the user to move from the main menu item to the fly-out really fast or the sub-menu disappears (IE8).
When my template was shorter than my vertical menu, the vertical menu behaves as overflow:hidden instead of ensuring that the container is the same height at the menu. Even adding a P tag below the menu does not cause the div to display properly. To do this, create a 3 column centered and fixed width CSS Sculptor 3 page, add a vertical menu of say 10 items to the left column, and delete the last pigeon-latin paragraph in the right column so it is shorter. The workaround is to fix the height of the left column, but that will not help if the menu is dynamic.
Lastly, when I selected in the theme Design => Current => Entire Navigation Route, all my menu options were displayed in their hover configuration on the home page.
Thanx for any feedback on these. Sorry I don't have a development example up yet. I'll try to get one up if you need it. I am using version 2.03 of CSSMW