Horizontal alignment of DynamicTextSpanner left text

[Simon Albrecht]

Hello list,

normally, horizontal alignment of grobs to other grobs is adjusted using 
self-alignment-X and parent-alignment-X—IIRC, this was homogenised some 
a couple years ago.

However, when wanting to adjust the alignment of a DynamicTextSpanner’s 
left bound, I found that this is much less clear for spanners. They have 
the parent-alignment-X component hidden behind the misleading property 
name attach-dir, and no default way of adjusting self-alignment-X via 
grob property (see this thread [1] for workarounds).

I suggest modifying line-spanner-interface to use self-alignment-X and 
parent-alignment-X in all subproperties of bound-details, and heeding 
these properties for DynamicTextSpanner and similar grobs.

Best, Simon


[1] https://lists.gnu.org/archive/html/lilypond-user/2022-01/msg00389.html