diff -r 231a0b1292f3 -r 2396457a8167 src/MainWindow.h
--- a/src/MainWindow.h	Sun Mar 27 20:38:25 2022 +0200
+++ b/src/MainWindow.h	Sun Mar 27 22:03:18 2022 +0200
@@ -19,6 +19,65 @@
 #include <QStandardItemModel>
 #include <QMenu>
 #include <QToolButton>
+#include <QApplication>
+#include <QDateTime>
+#include <QDebug>
+#include <QDir>
+// #include <QDomDocument>
+#include <QFile>
+#include <QList>
+#include <QMetaProperty>
+#include <QObject>
+#include <QSettings>
+#include <QString>
+#include <QTextStream>
+#include <QTranslator>
+#include <QtSql>
+#include <QUuid>
+#include <QStyle>
+#include <QPlainTextEdit>
+#include <QMessageBox>
+#include <QLabel>
+#include <QImage>
+#include <QImageReader>
+#include <QImageWriter>
+#include <QColorSpace>
+#include <QGraphicsView>
+#include <QFileDialog>
+#include <QXmlStreamReader>
+#include <QXmlStreamWriter>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QMap>
+#include <QPrinter>
+#include <QWidget>
+
+
+typedef struct IniMySQL
+{
+    QString host;               ///< MySQL host
+    QString port;               ///< MySQL port
+    QString name;               ///< MySQL database
+    QString user;               ///< MySQL username
+    QString pass;               ///< MySQL password
+    QString charset;            ///< MySQL character encoding
+} IniMySQL;
+
+static IniMySQL dbProd;
+static IniMySQL dbDev;
+
+typedef struct IniMQTT
+{
+    QString host;               ///< MQTT host
+    QString port;               ///< MQTT port
+    QString user;               ///< MQTT username
+    QString pass;               ///< MQTT password
+} IniMQTT;
+
+static IniMQTT mqttProd;
+static IniMQTT mqttDev;
+
 
 namespace Ui {
 class MainWindow;
@@ -29,7 +88,7 @@
     Q_OBJECT
 
 public:
-    explicit MainWindow(QWidget *parent = 0);
+    explicit MainWindow(bool useDevelopOption, bool startConfigOption, QWidget *parent = 0);
     ~MainWindow();
 
     // Keep pointers to new windows.
@@ -85,6 +144,16 @@
 
 private:
     Ui::MainWindow *ui;
+
+    /**
+     * @brief Read user settings for the MySQL connection.
+     */
+    void readsettings();
+
+    /**
+     * @brief Write or update the user settings for the MySQL connection.
+     */
+    void writesettings();
 };
 
 #endif