On 2017-05-28 14:14, Eli Zaretskii wrote:> There's a string there, so those properties are processed when the
> display engine traverses the string characters.

Thanks. Understood.

>> Could the same thing happen here?
> 
> No, because there's no string.  There's just buffer text and nothing
> else.
> 
> Maybe we could extend the line-prefix property to support left-fringe
> and right-fringe specs.

Hey, it works!

  (insert (propertize "AA" 'line-prefix (propertize "_" 'display '(left-fringe right-arrow))))

:)

Anything bad with this?

>>> Are overlays really so slow that you are prepared to jump through such
>>> hoops?
>>
>> Definitely :) I need these markers for a literate-programming buffer where roughly every other line has a marker.  On a 10k lines file, overlays are entirely impractical.
> 
> Can you show a simple example where having 5K overlays in a buffer
> cause significant slowdown?  I mean, just having 5K overlays, without
> any additional bells and whistles.  What exactly is slowed down?

My mode uses overlays for other purposes, and this slows all of it down.

Thanks for your time and answers :)
Clément.