I got really weird error (invalid panel passed to top_panel) when there
was no such call, so I guess there was some memory corruption.
formatLine is the only suspect, but when I put in the guard, the error
wasn't reproduced (just scrolling through qwaq's makefile in a big
window).
It's a fairly high-level wrapper for TextBuffer in that it implements
file ops (load/save), searching, navigation, and formatting (simple
line-oriented with tab stops (currently at 4 spaces)).