The Preview panel provides you a WYSIWYG (What You See Is What You Get) view of your work.

Buttons appear on the Global Background according to the specified Layout, as well as individual button's Properties (attributes).

You can interact with the buttons to see their dynamic behavior in action. Simply pass the mouse over the buttons, press on them, then release the mouse - as you normally would. The buttons don't do or execute anything of course, but they give you proper visual feedback as they transition between various states.

You can make all buttons Downable (i.e., Sticky, working in all 8 states) by ensuring the "Downable (Sticky)" checkbox on the left-hand side of the Property Panel is checked.

You can disable and re-enable individual buttons by right-clicking the desired button and invoking the "Toggle Enabled State" command. The button will enter one of the Disabled states depending on whether it was in the Downed state when you disabled it. In other words, disabling a normal "up" button will make it Disabled, while disabling a Downed button will make it Downed Disabled.

Double-clicking on the Global Background opens the Layout dialog.