This makes no sense in expert mode either but is harder to solve. :)

This would alles changing things that are deliberately left out in the 
props panel.

Not above.

Also add controls to non-expert mode.

Connect all lists of that section.

Setting the mode in the constructor was too early.

The selected section is replaced with the new section when empty. 
Otherwise the new section is appended below the selected section.
There is no way to influence this behaviour (contrary the 
section-insert-dialog).