Breaks key shortcuts involving media keys

Submitted by Stéphane Gourichon

Assigned to Andrzej

Link to original bug (#16363)

Description

Opened after discussion on IRC on 2019-01-09 around 16:45 UTC and again on 2019-01-10 around 11:00 UTC. Thanks for the hints helping to understand what happens!

Overview

Xfce4-pulseaudio-plugin "hides" media keys from xfsettingsd, silently preventing to use key shortcuts involving media keys.

How to reproduce

• Launch xfce4-keyboard-settings

Control experiment:

• in the "keyboards shortcuts" define a combination that runs "xmessage foo" attached to a regular key combination, like Ctrl-Alt-Shift-H.
• press Ctrl-Alt-Shift-H, see the xmessage window "foo"

Bug-reproducing experiment:

• in the "keyboards shortcuts" define a combination that runs "xmessage foo" attached to a media key, like Play Stop PlayPause Next Previous .
• press the media key

Actual Results: no xmessage window "foo"

Expected Results: see the xmessage window "foo"

Additional information

• Observed in Xubuntu 19.10 with default configuration; xfce 4.14.
• Removing xfce4-pulseaudio-plugin from panel allows to get expected behavior, but at the cost of losing all the plugin features.
• In plugin preferences, disabling "Enable multimedia keys for playback control" works around the bug, but at the cost of losing the features.

What is the core of the bug?

• Violation of the Principle of Least Surprise ( https://en.wikipedia.org/wiki/Principle_of_least_astonishment ) because xfce4-keyboard-settings allows to define shortcut but they don't actually work.

How could it be fixed?

Suggested behavior: when "Enable multimedia keys for playback control" is active, xfce4-pulseaudio-plugin would handle the shortcut then pass it on so that xfsettingsd can see if there is an additional user-defined shortcut and run it.