Add "About Qt" menu option to show built-in Qt About dialog

- Most Qt programs do this, and it can be useful to find out what version of Qt was built against.

src/qt/bitcoingui.cpp

@@ -56,6 +56,7 @@ BitcoinGUI::BitcoinGUI(QWidget *parent):
     walletModel(0),
     encryptWalletAction(0),
     changePassphraseAction(0),
+    aboutQtAction(0),
     trayIcon(0),
     notificator(0)
 {
@@ -208,7 +209,10 @@ void BitcoinGUI::createActions()
     quitAction->setMenuRole(QAction::QuitRole);
     aboutAction = new QAction(QIcon(":/icons/bitcoin"), tr("&About %1").arg(qApp->applicationName()), this);
     aboutAction->setToolTip(tr("Show information about Bitcoin"));
-    aboutAction->setMenuRole(QAction::AboutQtRole);
+    aboutAction->setMenuRole(QAction::AboutRole);
+    aboutQtAction = new QAction(tr("About &Qt"), this);
+    aboutQtAction->setToolTip(tr("Show information about Qt"));
+    aboutQtAction->setMenuRole(QAction::AboutQtRole);
     optionsAction = new QAction(QIcon(":/icons/options"), tr("&Options..."), this);
     optionsAction->setToolTip(tr("Modify configuration options for bitcoin"));
     optionsAction->setMenuRole(QAction::PreferencesRole);
@@ -225,6 +229,7 @@ void BitcoinGUI::createActions()
     connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
     connect(optionsAction, SIGNAL(triggered()), this, SLOT(optionsClicked()));
     connect(aboutAction, SIGNAL(triggered()), this, SLOT(aboutClicked()));
+    connect(aboutQtAction, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
     connect(openBitcoinAction, SIGNAL(triggered()), this, SLOT(showNormal()));
     connect(encryptWalletAction, SIGNAL(triggered(bool)), this, SLOT(encryptWallet(bool)));
     connect(changePassphraseAction, SIGNAL(triggered()), this, SLOT(changePassphrase()));
@@ -252,6 +257,7 @@ void BitcoinGUI::createMenuBar()
 
     QMenu *help = appMenuBar->addMenu(tr("&Help"));
     help->addAction(aboutAction);
+    help->addAction(aboutQtAction);
 }
 
 void BitcoinGUI::createToolBars()

src/qt/bitcoingui.h

@@ -82,6 +82,7 @@ private:
     QAction *exportAction;
     QAction *encryptWalletAction;
     QAction *changePassphraseAction;
+    QAction *aboutQtAction;
 
     QSystemTrayIcon *trayIcon;
     Notificator *notificator;