This Month in Mutter & GNOME Shell | March 2020

During March, GNOME Shell and Mutter saw their 3.36.0 and 3.36.1 releases, and the beginning of the 3.38 development cycle. We’ve focused most of the development efforts  on fixing bugs before starting the new development cycle.

From the development perspective, the 3.36.0 release was fantastic, and the number of regressions relative to the massive amount of changes that happened during the last cycle was remarkably small.


GNOME Shell saw continued improvements in its new Extensions app. New APIs were added to the Shell, which allows moving the Extensions app away into its own codebase. It also allows Shell to expose fewer interfaces through D-Bus.  The Extensions app is now available on Flathub.

A number of other small bugs and crashes were fixed for 3.36.1. Notably, the blur effect now works properly with fractional scaling.

Initial 3.38 work includes an improved Bluetooth state reporting, and the usage of JavaScript promises to simplify various asynchronous operations.


Following the 3.36.0 release, Mutter received various fixes to window streaming support. In contrast to streaming entire monitors, which was working properly, window streaming had a few quirks and misbehaviors. For 3.36.1, we’ve tracked down many issues around it and fixed them. Streaming windows is also done using DMA buffer sharing mechanisms.

On Wayland, sometimes new windows would use the wrong position to animate, leading to the zoom in animation look broken. This issue was fixed as well. Pasting images from Firefox does not freeze apps, specially Xwayland apps, anymore. We also fixed a series of bugs where Xwayland windows would show a black border when resizing.

Mutter now properly handles hardware cursors when hotplugging GPUs, and cursor hotspots now work correctly again on virtual machines. Sometimes cursors would rotate wrongly when on already rotated displays, and this was also fixed.

On the X11 front, Mutter now respects manually configured RandR panning on X11, and a bug preventing the correct monitor scale from being applied on X11 was also fixed.

Mutter now also finally respects the “middle mouse button” emulation setting exposed via GSettings.