Re: Combining face and map stuff

[Eli Zaretskii]

> From: Miles Bader <address@hidden>
> Date: Mon, 04 Oct 2010 18:03:04 +0900
> Cc: Stefan Monnier <address@hidden>, address@hidden
> 
> Eli Zaretskii <address@hidden> writes:
> > How would the display engine know which "plane" to use for rendering
> > each character?  Or are you suggesting to hard-code a fixed list of
> > "planes" in the display code?
> 
> It sounds like he's saying it would use their union, with a
> property-specific function used to compute that union.
> 
> [and that the union computation could be done at "property setting time"
> rather than at display time, to avoid speed problems.]

I'm probably missing something here: if the union is computed at
put-text-property time, then how is this different from what we have
now?  That union will have all the properties of the character lumped
together, just like what we have now, right?  What am I missing?