/usr/bin/NSPanelTest is in gnustep-examples 1:1.4.0-1+b2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../lib/GNUstep/Applications/NSPanelTest.app/NSPanelTest
/usr/bin/../lib/GNUstep/Applications/NSPanelTest.app/NSPanelTest