See attached screenshots (comparing the GNOME Terminal app UI in both native GTK
and with Swing's GTK L&F, using both Blueprint and Clearlooks themes, taken on
Solaris Nevada b27a with Mustang b63). I've also attached a partial implementation
of the Terminal UI using Swing for comparison purposes. Can you find six differences between the panels?
  1) menu item text in Swing is not justified as far left as native (Swing seems to
     add unnecessary padding on left side)
  2) arrow pointing to submenu in Swing is not justified as far right as native
  3) menu item text in Swing is crammed together with accelerator text (Swing does
     not add enough padding between item text and accelerator text)
  4) accelerator text in Swing is not justified as far right as native
  5) not shown in the attached screenshots, but Swing renders menus differently
     from native when they contain a mixture of plain, checkbox, and
     radio button menu items (the text of these items should be aligned
     horizontally; if there is a checkbox or radio button, that should not
     affect this alignment)

Many of these issues are probably in Synth code, so we should fix them at the root
so that the GTK L&F looks more like native, and so that Synth is more usable out of
the box.