Currently some modes share tool keymaps, we might want to disable
this since it's confusing editing one thing in multiple places.
However this should be resolved in the tool definitions.
Misleading name since it's between 0..1.
Use as a keyword argument to prepare for keyword only args.
Also document that leaving unset has special behavior.
* Remove unnecessary big margins after triangle icons (esp. for keymap items they where waaay to big)
* Remove ugly margin after "Foo (Global)" entries
* Add little margin after expanded key maps
Actually, 3 issues here:
* Keymap items of "Foo (Global)" maps weren't indented enough
* Items after a opened "Foo (Global)" map were indented too much (col was overridden then).
