GNOME's Mutter Sees Big Rework, Striving For Multi-DPI Rendering
Jonas has been reworking Mutter to draw monitor contents to individual frame-buffers rather than targeting a single frame-buffer, in order to support situations of having multiple monitors with a desire to have independent DPI changes for each display (e.g. one HiDPI display and other displays that are not), etc. Jonas summarized it with this bug report.
Hours ago were this big slew of commits including the concept of a MetaRenderer, changes to monitor logic management, regional state rendering, and other work related to drawing to multiple frame-buffers and dealing with monitor handling.
This work is building up for GNOME 3.22 and will presumably have more to report on this area of Mutter in the near future.