On 2017-02-05 13:28, Eli Zaretskii wrote:
> What will happen if you have 2 overlays like this:
> 
>                +------------- OV2 -------+
>    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>    +------- OV1 ---------+
> 
> and OV2 has a higher priority than OV1?

The two overlays get sorted as (OV1 OV2).  Then my code applies OV1's properties to the range covered by OV1, and OV2's properties to the range covered by OV2, which override those of OV1 in the overlapping range (except in the case of face properties, which get appended instead of overriding).

Clément.