When the kerning mode is set to locked kerning the shortcuts to modify the fitting do not work. I wonder if this is by design or a bug. If the former, it is inconsistent with the manual which says (p.45):
The kerning and locked-kerning settings both show
kerning, but the latter disables the editing of the kerning. This
can be useful if you want to edit the sidebearings without
accidentally manipulating kerning pairs.
Thanks Rainer. So ‘locked kerning’ is locked metrics?
EDIT: Sorry, could have answered this myself. For the record, here’s the bit from the 2.3 manual (p.46):
The kerning and locked-kerning settings both show
kerning, but the latter disables the editing of the spacing.
This can be useful if you want to edit the kerning without
accidentally manipulating spacing.