thermostat: introduce QStackedwidget

soft/thermostat/inc/mainwindow.h

@@ -9,6 +9,7 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
+#include <QStackedWidget>
 #include <QMainWindow>
 #include <QPushButton>
 #include <QtWidgets>
@@ -32,6 +33,7 @@ private:
 	QPushButton m_state_btn;
 	QVector<ZoneItem *> m_zones;
 	QTimer *m_timer;
+	QStackedWidget m_central_widget;
 	void update_state_btn(enum power_states st);
 	double get_target_temperature(int room_idx);
 	bool get_heater_order(int room_idx);

soft/thermostat/src/mainwindow.cpp

@@ -66,10 +66,12 @@ MainWindow::MainWindow(QWidget *parent) :
 	QWidget *mainWidget = new QWidget;
 	mainWidget->setLayout(mainLayout);
 
+	m_central_widget.addWidget(mainWidget);
+
 	/*
 	 * Top widget
 	 */
-	setCentralWidget(mainWidget);
+	setCentralWidget(&m_central_widget);
 
 	setWindowTitle(tr("Sorico's thermostat"));