[Qt] misc small Mac related changes/cleanups

- cleanup Info.plist.in and specify high DPI mode enable command as per
  http://blog.qt.digia.com/blog/2013/04/25/retina-display-support-for-mac-os-ios-and-x11/
- move setting of QApplication::setAttribute() to bitcoin.cpp and add
  attribute for enabling use of high DPI pixmaps for Qt >= 5.1
- add missing setWindowTitle() on Mac
- cleanup Mac / non-Mac setup in bitcoingui.cpp

share/qt/Info.plist.in

@@ -4,18 +4,25 @@
 <dict>
   <key>CFBundleIconFile</key>
   <string>bitcoin.icns</string>
+
   <key>CFBundlePackageType</key>
   <string>APPL</string>
+
   <key>CFBundleGetInfoString</key>
   <string>@CLIENT_VERSION_MAJOR@.@CLIENT_VERSION_MINOR@, Copyright © 2009-@COPYRIGHT_YEAR@ The Bitcoin developers</string>
+
   <key>CFBundleShortVersionString</key>
   <string>@CLIENT_VERSION_MAJOR@.@CLIENT_VERSION_MINOR@</string>
+
   <key>CFBundleVersion</key>
   <string>@CLIENT_VERSION_MAJOR@.@CLIENT_VERSION_MINOR@</string>
+
   <key>CFBundleSignature</key>
   <string>????</string>
+
   <key>CFBundleExecutable</key>
   <string>Bitcoin-Qt</string>
+
   <key>CFBundleIdentifier</key>
   <string>org.bitcoinfoundation.Bitcoin-Qt</string>
 
@@ -69,7 +76,11 @@
       <string>Owner</string>
     </dict>
   </array>
+
+  <key>NSPrincipalClass</key>
+    <string>NSApplication</string>
+
   <key>NSHighResolutionCapable</key>
-  <true/>
+    <string>True</string>
 </dict>
 </plist>

src/qt/bitcoin.cpp

@@ -200,6 +200,13 @@ int main(int argc, char *argv[])
 
     Q_INIT_RESOURCE(bitcoin);
     QApplication app(argc, argv);
+#if QT_VERSION > 0x050100
+    // Generate high-dpi pixmaps
+    QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+#endif
+#ifdef Q_OS_MAC
+    QApplication::setAttribute(Qt::AA_DontShowIconsInMenus);
+#endif
 
     // Register meta types used for QMetaObject::invokeMethod
     qRegisterMetaType< bool* >();

src/qt/bitcoingui.cpp

@@ -69,28 +69,32 @@ BitcoinGUI::BitcoinGUI(bool fIsTestnet, QWidget *parent) :
 {
     GUIUtil::restoreWindowGeometry("nWindow", QSize(850, 550), this);
 
-#ifndef Q_OS_MAC
     if (!fIsTestnet)
     {
         setWindowTitle(tr("Bitcoin") + " - " + tr("Wallet"));
+#ifndef Q_OS_MAC
         QApplication::setWindowIcon(QIcon(":icons/bitcoin"));
         setWindowIcon(QIcon(":icons/bitcoin"));
+#else
+        MacDockIconHandler::instance()->setIcon(QIcon(":icons/bitcoin"));
+#endif
     }
     else
     {
         setWindowTitle(tr("Bitcoin") + " - " + tr("Wallet") + " " + tr("[testnet]"));
+#ifndef Q_OS_MAC
         QApplication::setWindowIcon(QIcon(":icons/bitcoin_testnet"));
         setWindowIcon(QIcon(":icons/bitcoin_testnet"));
-    }
 #else
-    setUnifiedTitleAndToolBarOnMac(true);
-    QApplication::setAttribute(Qt::AA_DontShowIconsInMenus);
-
-    if (!fIsTestnet)
-        MacDockIconHandler::instance()->setIcon(QIcon(":icons/bitcoin"));
-    else
         MacDockIconHandler::instance()->setIcon(QIcon(":icons/bitcoin_testnet"));
 #endif
+    }
+
+#if defined(Q_OS_MAC) && QT_VERSION < 0x050000
+    // This property is not implemented in Qt 5. Setting it has no effect.
+    // A replacement API (QtMacUnifiedToolBar) is available in QtMacExtras.
+    setUnifiedTitleAndToolBarOnMac(true);
+#endif
 
     // Create wallet frame and make it the central widget
     walletFrame = new WalletFrame(this);