Contains the GUI classes.
A `JFrame` is created during the startup of the program. This frame will be either a {@link net.sf.freecol.client.gui.FullScreenFrame} or a {@link net.sf.freecol.client.gui.WindowedFrame} based on the capabillities of the system (or the user's manual choice). A {@link net.sf.freecol.client.gui.Canvas} will then be added to the frame.
`Canvas` is the main container for the other GUI components in FreeCol. This class is where the panels, dialogs and menus are added. In addition, `Canvas` is the component in which the map graphics are displayed.
Other important classes:

- The {@link net.sf.freecol.client.gui.GUI} contains the methods to draw the map upon `Canvas`, in addition to other useful gui-methods.
- The {@link net.sf.freecol.client.gui.FreeColMenuBar} is the menu bar that is displayed on top corner of the `Canvas`.