I want to accomplish two things:
Be able to minimize long function definitions and other blocks of code. To this end, I grouped each such block with a Text-style title that I can double-click to open or close the block. Other styles, like Chapter or Subsection, seemingly have a will of their own and do all kinds of crazy things - make one big group of all cells in the notebook, fail to respond to "Ungroup Cells", re-absorb cells that I try to move out of the group - so I avoid those.
Have one second-level group of all the block+title groups, so that I can select and evaluate it. "Group Cells" doesn't work here - it just merges the cells together instead of grouping them.
I think I'm supposed to use the other styles to accomplish this, but I don't know how to get them to behave.