help gnome users find a way to get statusicon back

[totaam]

Follow up for #406.

If we find that the topicons / appindicator extension is not installed, show a warning dialog and offer to install the package (by calling packagekit? only if we know the package name?)
Have an option to not show the dialog again (and save to .local/share/xpra/conf.d/80_gnomeshell_warning.conf?).

If the extension is installed but not enabled, offer to enable it:

• How to activate/deactivate a gnome-shell extension from command line - gnome-shell-extension-tool did not work for me on Fedora.. could be wrong extension name?
• 11.2. enabling maching wide extensions - again, this sounds great but doesn't do anything
• show the gnome-tweaks tool?

Once all of this has been done, offer to restart gnome shell

• How to properly start a Gnome-Shell extension via command line? - but killall -HUP gnome-shell logged me out... via dbus?

[totaam]

See also: AppIndicator3 Indicator props connected: True if we have a reasonable expectation of being displayed through this object. You should hide your TrayIcon if so.

[totaam]

Too hard to make this work reliably on all platforms (even just RPM platforms), so WONTFIX.

A "better" solution would be #476, see #2161#comment:3

[totaam]

The commit above adds an xpra-client-gnome package.
The post install script will try to enable the appindicator extension for active users.

Enabling system wide is apparently possible but due to the configuration file format, there's a risk we might actually remove existing settings by configuring the enabled-extensions option.
Parsing a potential existing value and appending to it would be preferable, but that's not easy in a shell script.