>> Is there any LilyPond documentation explaining that it is possible
>> to switch off (set to ##f) the self-alignment-X property?
>
> Now it is :-)
Actually, it was documented before, too, namely in the IR:
‘self-alignment-X’ (number):
Specify alignment of an object. The value ‘-1’ means left
aligned, ‘0’ centered, and ‘1’ right-aligned in X direction.
Other numerical values may also be specified - the unit is
half the object width. If not a number, align on the object’s
reference point.
Note the 'if not a number' part – you could also use `"foo"` instead
of `##f` to get the same effect.
Werner
