Re: Approximates cross-staff slurs in VerticalAxisGroup vertical-skylines. (issue 6498077)

[address@hidden]

On 8 sept. 2012, at 18:43, address@hidden wrote:

> 
> On 8 sept. 2012, at 09:06, Keith OHara <address@hidden> wrote:
> 
>> On Fri, 07 Sep 2012 09:23:08 -0700, address@hidden <address@hidden> wrote:
>> 
>>> 
>>> On 7 sept. 2012, at 09:34, address@hidden wrote:
>>> 
>>>> Having the invisible Grobs taking up space will confuse the innocent.
>>> 
>>> I tried to add comments about this in the source - perhaps the CG needs an 
>>> invisible grob bit, as we have StemStubs and SpanBarStubs as well.
>> 
>> People who have read the source code and contributors guide are not "the 
>> innocent".
> 
> Ah, ok. I can put the idea of stubs in the docs too - this is an entirely 
> comprehensible concept for those who understand basic engraving principles, 
> as this is how engravers reserve space in many cases. They use physical 
> objects that take up space but are never printed to block other objects.

Did some thinking, and I think it'd be good to have a separate patch after this 
with a section in Chapter 1 of the notation manual about invisible grobs.  In 
LilyPond, we currently have:

--) Collection grobs that facilitate alignment (DynamicLineSpanner, 
ScriptColumn, NoteColumn)
--) Spacer grobs that block other ones (LeftEdge, StemStub, SpanBarStub)

Both of these categories are related in that they're invisible and therefore 
may not be intuitive to override.  I'm not very good at doc writing but if no 
one else wants to write about these grobs I could give it a shot.

Cheers,
MS