AWT status

[Tom Tromey]

This weekend I did some AWT hacking.

Now a lot of TestAWT works for me (using the Gtk+ JNI peers and gcj).
In particular all the windows pop up and the layout bugs all seem to
be gone.

Some bugs remain:

* The Cursors window displays things oddly (the button appears twice,
  though it can be hard to find the second one since it is obscured;
  you have to resize the window a lot to see it)

* Dialog buttons don't work
* Ditto File

* The Radio Button window works but the second time you pop it up you
  get Gtk errors.  This is due to a problem I introduced in the peers;
  I didn't realize that the native state support required a special
  field in the object.  This needs some rethinking, since adding a
  field to CheckboxGroup is probably not what we want to do.

* Font peers haven't been implemented yet.
* Radio button peers need some special code to let them switch modes
  at runtime (you can't see this problem with TestAWT)

I think there are more tree lock bugs to fix, but I haven't gone
looking for them yet.  Basically I didn't look for any of them -- I
just audited a few classes, adding the synchronization where required.
This same procedure should be copied for other classes.

Tom