[pygame] Driftwood Interface Code

[Kris Schnee <kschnee@xxxxxxxxxx>]

<http://kschnee.xepher.net/code/Driftwood%20Demo.zip>
<http://kschnee.xepher.net/pics/070428driftwood.jpg>

Here's a revised version of my interface code, Driftwood. So far I've 
got a basic widget, a button, and a multi-line text display, plus an 
optional system for coordinating the various screens of a game. I'd 
released a version of Driftwood before, but this one has better-designed 
code that's hopefully easier to understand. The standard window border 
also looks better than before. It's free software, and I plan to release 
a version with more classes the same way.

The demo shows a mock title screen with a working Quit button and an 
Options button that takes you to a mock options screen. The options 
screen has a Back button, a text area, and a test button that adds text 
to the text area. There's also a simpler demo class.

Unlike last time, the widgets normally draw directly to the screen 
instead of blitting completely to a hidden surface and updating only 
sometimes. Each widget knows its actual screen position and isn't 
confined to the area of its official parent widget.

I'm having a hard time figuring out the exact scrolling behavior I want 
in the TextDisplay class. It's meant to do this when told to add text:
-Add the new rendered text one character at a time to my display 
surface, part of which is blitted each frame to the screen so that I can 
hold more text than is actually shown.
-If the next character would be drawn to a spot below the currently 
visible area, move the visible area down by one line.
-If the next character would actually go below the drawing surface, copy 
a chunk of the current text upwards by one line, and clear the bottom line.

Not sure how to handle deletion of text either.

Kris