New default theme

[Owen Taylor <otaylor redhat com>]

I just checked in the first major change to GTK+'s default theme
since the beginning of time.

The new look is basically the Raleigh theme I did for GTK+-1.2, so
yes, it's boring and Windowesque, but I also think it's reasonably
attractive (especially for something done by me rather than a better
qualified artist), and plain enough to not get annoying too quickly.

So, the major changes are:

 - Windows-style Check and Radio buttons. I didn't have a chance
   to do if (strcmp (uname, "timj") == 0) use_diamonds(), so Tim
   is going to have to suffer for now ;-)

   (The several times the issue has come up, I heard no other
   requests for the diamond shape, so I'm inclined to follow
   my instinct and Windows here. Fairly convincing arguments
   have been made that a Mac/etc. style "button" is better
   than the Windows style indicator, but I haven't seen a
   way of drawing this that I really like. And the Windows-style
   indicators are certainly familiar to a lot of people.
   I'd consider this still an open issue.)

 - Focus is done Windows (etc.) style with the focus being a 
   dotted line inside the button.

   The default is now drawn as a black line like the old focus
   indication.

 - No more triangular buttons. Arrows are universally represented by a
   black arrow on a square button (or flat, for menus). Similarly, the
   weird Motif option menu tab is gone, replaced by a double arrow.

 - Slider and scrollbar troughs are now half-depth, giving a bit  
   of a lower-contrast / thinice look.

Assuming we don't make major changes (and I'm not opposed to still
changing the visual language some more), areas that I think can be
touched up to advantage:

 - The scrollbar bevelling can still be improved some; the scrollbar
   thumb tends to look a bit slanted. Having looked at the Java
   Metal scrollbar in detail, I have some ideas of how this can
   be done better now.

 - I'm not completely happy with the arrows with the square base.
   I want to try using a equaliteral triangle with an anti-aliasing
   color instead.
 
 - The spinbutton is too busy. Removing the center line probably
   helps. Tigert has suggested making the arrows completely flat
   and on a white background, but I think this looks a little odd
   and it isn't clear they are buttons.

Once we are happy with the rough outline, I'd also like to see someone
do a theme engine that takes the visual language, and softens, rounds,
etc, it for cases where the extra weight of gradients and a few
pixmaps isn't a problem.

Regards,
                                        Owen