There are a few problems with the Quit... dialog in Component test, including the fact that it's not large enough to get at the buttons on any platform other than the Macintosh. The severe problem, however, is the fact that if you use the native environment's methods of dismissing popup dialogs, the appletviewer will hang.
To reproduce, on any Win32 or Solaris...
run awt/ComponentTest
Select File... Quit
When the too-small dialog appears, use alt-f4 or dismiss to make it go away. Now all appletviewer windows will simply beep at you if anything; it's hung.