Attaching menus and tool bars

I have a layout and I attach a menu to it thus:

ezMainMenu = dhxLayout.cells("a").attachMenu();

However, I am confused as to what this means.

I still have to create a DIV for the menu and ensure its position is fine.

Given that I built the menu and then positioned it - what is attaching really doing for me? Will I get some benefit down the line when events fire across components?

Sorry if this is a bit noobish.

Many thanks in advance.