Qt: Add option to hide the system tray icon

My changes leave all tray icon and menu creation/initialization logic
untouched. It only shows or hides the icon according to the setting.

A new checkbox was added to the OptionsDialog under the Window tab. A
bool option named "hideTrayIcon" was added to OptionsModel. This
checkbox was mapped like other all options to the OptionsModel.

A signal was added to the OptionsModel for broadcasting changes the the
hideTrayIcon option. This signal was connected to a new slot added to
BitcoinGUI named setTrayIconVisible(bool). The slot simply hides or
shows the trayIcon in BitcoinGUI according to the parameter recieved.

src/qt/bitcoingui.cpp

@@ -474,6 +474,16 @@ void BitcoinGUI::setClientModel(ClientModel *clientModel)
         }
 #endif // ENABLE_WALLET
         unitDisplayControl->setOptionsModel(clientModel->getOptionsModel());
+        
+        OptionsModel* optionsModel = clientModel->getOptionsModel();
+        if(optionsModel)
+        {
+            // be aware of the tray icon disable state change reported by the OptionsModel object.
+            connect(optionsModel,SIGNAL(hideTrayIconChanged(bool)),this,SLOT(setTrayIconVisible(bool)));
+        
+            // initialize the disable state of the tray icon with the current value in the model.
+            setTrayIconVisible(optionsModel->getHideTrayIcon());
+        }
     } else {
         // Disable possibility to show main window via action
         toggleHideAction->setEnabled(false);
@@ -535,7 +545,7 @@ void BitcoinGUI::createTrayIcon(const NetworkStyle *networkStyle)
     QString toolTip = tr("%1 client").arg(tr(PACKAGE_NAME)) + " " + networkStyle->getTitleAddText();
     trayIcon->setToolTip(toolTip);
     trayIcon->setIcon(networkStyle->getTrayAndWindowIcon());
-    trayIcon->show();
+    trayIcon->hide();
 #endif
 
     notificator = new Notificator(QApplication::applicationName(), trayIcon, this);
@@ -1044,6 +1054,14 @@ void BitcoinGUI::showProgress(const QString &title, int nProgress)
         progressDialog->setValue(nProgress);
 }
 
+void BitcoinGUI::setTrayIconVisible(bool fHideTrayIcon)
+{
+    if (trayIcon)
+    {
+        trayIcon->setVisible(!fHideTrayIcon);
+    }
+}
+
 static bool ThreadSafeMessageBox(BitcoinGUI *gui, const std::string& message, const std::string& caption, unsigned int style)
 {
     bool modal = (style & CClientUIInterface::MODAL);

src/qt/bitcoingui.h

@@ -218,6 +218,9 @@ private Q_SLOTS:
 
     /** Show progress dialog e.g. for verifychain */
     void showProgress(const QString &title, int nProgress);
+    
+    /** When hideTrayIcon setting is changed in OptionsModel hide or show the icon accordingly. */
+    void setTrayIconVisible(bool);
 };
 
 class UnitDisplayStatusBarControl : public QLabel

src/qt/forms/optionsdialog.ui

@@ -504,6 +504,16 @@
        <string>&amp;Window</string>
       </attribute>
       <layout class="QVBoxLayout" name="verticalLayout_Window">
+       <item>
+        <widget class="QCheckBox" name="hideTrayIcon">
+         <property name="toolTip">
+          <string>&amp;Hide the icon from the system tray.</string>
+         </property>
+         <property name="text">
+          <string>Hide tray icon</string>
+         </property>
+        </widget>
+       </item>
        <item>
         <widget class="QCheckBox" name="minimizeToTray">
          <property name="toolTip">

src/qt/optionsdialog.cpp

@@ -198,6 +198,7 @@ void OptionsDialog::setMapper()
 
     /* Window */
 #ifndef Q_OS_MAC
+    mapper->addMapping(ui->hideTrayIcon, OptionsModel::HideTrayIcon);
     mapper->addMapping(ui->minimizeToTray, OptionsModel::MinimizeToTray);
     mapper->addMapping(ui->minimizeOnClose, OptionsModel::MinimizeOnClose);
 #endif
@@ -243,6 +244,19 @@ void OptionsDialog::on_cancelButton_clicked()
     reject();
 }
 
+void OptionsDialog::on_hideTrayIcon_stateChanged(int fState)
+{
+    if(fState)
+    {
+        ui->minimizeToTray->setChecked(false);
+        ui->minimizeToTray->setEnabled(false);
+    }
+    else
+    {
+        ui->minimizeToTray->setEnabled(true);
+    }
+}
+
 void OptionsDialog::showRestartWarning(bool fPersistent)
 {
     ui->statusLabel->setStyleSheet("QLabel { color: red; }");

src/qt/optionsdialog.h

@@ -50,6 +50,8 @@ private Q_SLOTS:
     void on_okButton_clicked();
     void on_cancelButton_clicked();
     
+    void on_hideTrayIcon_stateChanged(int fState);
+
     void showRestartWarning(bool fPersistent = false);
     void clearStatusLabel();
     void updateProxyValidationState();

src/qt/optionsmodel.cpp

@@ -51,9 +51,14 @@ void OptionsModel::Init(bool resetSettings)
     // These are Qt-only settings:
 
     // Window
+    if (!settings.contains("fHideTrayIcon"))
+        settings.setValue("fHideTrayIcon", false);
+    fHideTrayIcon = settings.value("fHideTrayIcon").toBool();
+    Q_EMIT hideTrayIconChanged(fHideTrayIcon);
+    
     if (!settings.contains("fMinimizeToTray"))
         settings.setValue("fMinimizeToTray", false);
-    fMinimizeToTray = settings.value("fMinimizeToTray").toBool();
+    fMinimizeToTray = settings.value("fMinimizeToTray").toBool() && !fHideTrayIcon;
 
     if (!settings.contains("fMinimizeOnClose"))
         settings.setValue("fMinimizeOnClose", false);
@@ -166,6 +171,8 @@ QVariant OptionsModel::data(const QModelIndex & index, int role) const
         {
         case StartAtStartup:
             return GUIUtil::GetStartOnSystemStartup();
+        case HideTrayIcon:
+            return fHideTrayIcon;
         case MinimizeToTray:
             return fMinimizeToTray;
         case MapPortUPnP:
@@ -242,6 +249,11 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
         case StartAtStartup:
             successful = GUIUtil::SetStartOnSystemStartup(value.toBool());
             break;
+        case HideTrayIcon:
+            fHideTrayIcon = value.toBool();
+            settings.setValue("fHideTrayIcon", fHideTrayIcon);
+    		Q_EMIT hideTrayIconChanged(fHideTrayIcon);
+            break;
         case MinimizeToTray:
             fMinimizeToTray = value.toBool();
             settings.setValue("fMinimizeToTray", fMinimizeToTray);

src/qt/optionsmodel.h

@@ -28,6 +28,7 @@ public:
 
     enum OptionID {
         StartAtStartup,         // bool
+        HideTrayIcon,           // bool
         MinimizeToTray,         // bool
         MapPortUPnP,            // bool
         MinimizeOnClose,        // bool
@@ -58,6 +59,7 @@ public:
     void setDisplayUnit(const QVariant &value);
 
     /* Explicit getters */
+    bool getHideTrayIcon() { return fHideTrayIcon; }
     bool getMinimizeToTray() { return fMinimizeToTray; }
     bool getMinimizeOnClose() { return fMinimizeOnClose; }
     int getDisplayUnit() { return nDisplayUnit; }
@@ -72,6 +74,7 @@ public:
 
 private:
     /* Qt-only settings */
+    bool fHideTrayIcon;
     bool fMinimizeToTray;
     bool fMinimizeOnClose;
     QString language;
@@ -87,6 +90,7 @@ private:
 Q_SIGNALS:
     void displayUnitChanged(int unit);
     void coinControlFeaturesChanged(bool);
+    void hideTrayIconChanged(bool);
 };
 
 #endif // BITCOIN_QT_OPTIONSMODEL_H