In 21.4.2 under RH6.2, moving the toolbar to the bottom and back via
"Options -> Display -> Default Toolbar Location -> Bottom" and then
back to "Top" does some damage:

1. When the toolbar is moved to the bottom, the overall size of the
window shrinks by about 4 lines.
2. When the toolbar is returned to the top, the window remains
shrunken, and the toolbar itself has gained a white bar.