KDE system tray support

[totaam]

• http://jjacky.com/statusnotifier/, code: https://github.com/jjk-jacky/statusnotifier
• https://github.com/davidedmundson/xembed-sni-proxy

[totaam]

For potential workarounds, see this mailing list post: new kde system tray.

See also: Dropbox: Systray icon not showing in KDE Plasma 5.2, which links to Where are my systray icons?.
Just like gnome3 (#476), they've broken this on purpose! No joke.

[totaam]

See also #1146.

[totaam]

See also https://bugzilla.redhat.com/show_bug.cgi?id=1231759

[totaam]

Some fixes for the systray size in r12242 + r12245, but it is still fundamentally broken in Fedora 23: see #1146#comment:5.
Click events are received bundled together when the mouse button is released, short clicks don't work at all (for whatever reason), you need to logout and login again or the systray won't show up the second time you launch xpra, etc..
What an awful mess. Indefensible.

[totaam]

It seems that all the libraries target GTK3, which we cannot use. (#640)

I guess we could use the source (ie: statusnotifier) to implement something using python-dbus:

#define WATCHER_NAME        "org.kde.StatusNotifierWatcher"
#define WATCHER_OBJECT      "/StatusNotifierWatcher"
#define WATCHER_INTERFACE   "org.kde.StatusNotifierWatcher"

#define ITEM_NAME           "org.kde.StatusNotifierItem"
#define ITEM_OBJECT         "/StatusNotifierItem"
#define ITEM_INTERFACE      "org.kde.StatusNotifierItem"

The "spec" seems to be here: [https://github.com/quassel/quassel/blob/master/interfaces/org.kde.StatusNotifierItem.xml].

Whatever we do, it's going to be bad: the spec does not expose the tray location so we'll have to continue the guessing game, it's menu orientated (because all apps only use the systray for showing menus apparently - sigh), etc... A huge step backwards.

[totaam]

Superseded by #2161