Composite retained drawing protocol

Submitted by Giuseppe Alfieri

Assigned to Olivier Fourdan @olivier

Link to original bug (#16438)

Description

Hi, I'm looking forward to allow full compatibility with DockbarX so I'm asking for this enhancement bound to a new planned freedesktop.org specification. In particular I'm pushing for development of Composite retained drawing protocol that exhibits a standard for window thumbnails.

Version: 4.12.0