It looks like my suspicion that "mate-power-backlight-helper" is referred to by absolute file name instead of by its polkit action is correct: Excerpt from src/gpm-brightness.c (https://git.mate-desktop.org/mate-power-manager/tree/src/gpm-brightness.c)
> static gboolean
> gpm_brightness_helper_set_value (const gchar *argument, gint value)
> {
> [...]
> /* get the data */
> command = g_strdup_printf ("pkexec " SBINDIR
> "/mate-power-backlight-helper --%s %i", argument, value);
> ret = g_spawn_command_line_sync (command, NULL, NULL, &exit_status,
> &error);
> [...]
> }
Next step: look at the GNOME source code, maybe it does things differently.
signature.asc
Description: This is a digitally signed message part
