Wayland

Users of the Wayland, a computer protocol which specifies the communication between a display server (called a Wayland compositor) and its clients, may find that there are some glitches in RawTherapee's user interface, for example all comboboxes (such as the Processing Profiles selector, the Film Simulation drop-down, etc.) work correctly only the first time they are used, and then do not respond until RawTherapee is restarted. This is not a bug in RawTherapee.

Reports indicate that the cause is an incompatibility between GTK+ and the Wayland compositor.

Users of the following distributions are most likely affected:
 * Fedora >=25
 * Ubuntu >=17.10 (Ubuntu 18.04 reverted to X11 due to Wayland issues)

Affected users are advised to:
 * Try switching the compositor to Weston.
 * Revert to X11 if problems persist.

More information:
 * https://fedoraproject.org/wiki/How_to_debug_Wayland_problems
 * Note that some information in the above document may not be up to date.