Actions
- Represent something the user can do
- a callback (or more than one)
- a label to use in menu items
- maybe a shorter label for toolbar buttons
- an icon
- state (sensitivity, visibility, etc)
- Can create an arbitrary number of menu items and toolbar buttons for an action
- properties and state of menu/toolbar items mirror the action they represent
- set action to disabled -> all widgets representing the action are disabled
- Different types of actions (extensible)