Aston Shell's Main Menu is made as a plug-in. Thus, most configuration changes should be done by editing the MenuEX plug-in's properties.
Start button's skins are set separately in Aston Options>Taskbar>Start Button menu. Main menu skins can be set in Aston Options>Plug-ins>Main menu with skins & icons>Setup plug-in.
So generally you'll have to create the following images:
As you can see, Start button has three states. No one forces you to make them all, but creating all three images can greatly improve your Theme's look and feel.
When using ANKs, Start button looks even better than ever. You can
make some really interesting stuff with it.
ANK frame list from Smanic's "My
corona" Start button mockup.
Start button can have transparent areas. This way you'll be able to
see the default Taskbar skin through it. Just remember, that Start button
is always centered vertically.
Still, in most cases transparency is redundant.
All the Main menu skin images, excluding separator must have the same height (and the same width is preferable as well). Separator's height can be either larger or smaller. No kind of transparency for the Main menu is supported. You can only adjust global transparency of the whole menu.
Main Menu from Dmitry Prosvirnin's "Aston
Desktop 1.9.1" Theme. This is a classic Main Menu skin for Aston 1.9.1
Themes.
Be careful, when selecting the size of Main Menu items: too large buttons can make your Theme look bloated. At the same time, too small buttons will bring you to navigation troubles. Dmitry Prosvirnin (the designer of Gladiators Software) has found a cute solution in his "Regeneration" Theme. He used menu items with a small height. That helped him to make a small menu where all the items are perfectly visible:
Dmitry Prosvirnin's compact menu
Surely, no icons can be displayed in such a way, but you can "fix" this disadvantage by using the minimum height of menu items set to 16px. This won't enlarge your menu a lot, but will make it look prettier.
With the implementation of footer element, 3PIC support and glass for Main Menu elements you're mostly limited by your imagination and Menu's rectangular form:
Fragment of "My Corona" Theme mockup by
Smanic: it uses most of new features of Aston 1.9.2