QSystemTrayIcon uses D-Bus StatusNotifier on Linux when possible

Implementing org.kde.StatusNotifier DBus interface
http://www.freedesktop.org/wiki/Specifications/StatusNotifierItem/
as well as org.canonical.dbusmenu for the limited purpose of showing
the tray icon's context menu.  If a desktop environment (such as
KDE or Unity) has a StatusNotifierWatcher listening, then tray icon
information is sent to be displayed by the tray implementation
instead of being rendered directly in an XEmbed window.  This is
necessary because some modern tray implementations no longer provide
XEmbed "hosting".

[ChangeLog][QPA][Xcb] QSystemTrayIcon uses StatusNotifier D-Bus
protocol when the desktop environment supports it

Task-number: QTBUG-31762
Done-with: Marco Martin <mart@kde.org>
Change-Id: I3b1f744d621eefc7e9c61d1469460ebfcc77fc54
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>

2 files changed, 10 insertions, 6 deletions

diff --git a/src/widgets/util/qsystemtrayicon.cpp b/src/widgets/util/qsystemtrayicon.cpp
index 30ef7e82e5..f322b083fc 100644
--- a/src/widgets/util/qsystemtrayicon.cpp
+++ b/src/widgets/util/qsystemtrayicon.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2015 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -69,8 +69,12 @@ QT_BEGIN_NAMESPACE
 
     \list
     \li All supported versions of Windows.
-    \li All window managers for X11 that implement the \l{freedesktop.org} system
-       tray specification, including recent versions of KDE and GNOME.
+    \li All window managers and independent tray implementations for X11 that implement the
+       \l{http://standards.freedesktop.org/systemtray-spec/systemtray-spec-0.2.html freedesktop.org}
+       XEmbed system tray specification.
+    \li All X11 desktop environments that implement the D-Bus
+       \l{http://www.freedesktop.org/wiki/Specifications/StatusNotifierItem/ StatusNotifierItem}
+       specification, including recent versions of KDE and Unity.
     \li All supported versions of Mac OS X. Note that the Growl
        notification system must be installed for
        QSystemTrayIcon::showMessage() to display messages on Mac OS X prior to 10.8 (Mountain Lion).
diff --git a/src/widgets/util/qsystemtrayicon_x11.cpp b/src/widgets/util/qsystemtrayicon_x11.cpp
index ba80734876..13562ee27a 100644
--- a/src/widgets/util/qsystemtrayicon_x11.cpp
+++ b/src/widgets/util/qsystemtrayicon_x11.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2015 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -344,8 +344,8 @@ void QSystemTrayIconPrivate::updateToolTip_sys()
 bool QSystemTrayIconPrivate::isSystemTrayAvailable_sys()
 {
     QScopedPointer<QPlatformSystemTrayIcon> sys(QGuiApplicationPrivate::platformTheme()->createPlatformSystemTrayIcon());
-    if (sys)
-        return sys->isSystemTrayAvailable();
+    if (sys && sys->isSystemTrayAvailable())
+        return true;
 
     // no QPlatformSystemTrayIcon so fall back to default xcb platform behavior
     const QString platform = QGuiApplication::platformName();