Restore to windowed, maximized, or full screen appropriately at start-up

interface/src/Application.cpp

@@ -516,7 +516,6 @@ Application::Application(int& argc, char** argv, QElapsedTimer &startup_time) :
 
 void Application::aboutToQuit() {
     _aboutToQuit = true;
-    setFullscreen(false); // if you exit while in full screen, you'll get bad behavior when you restart.
 }
 
 Application::~Application() {

interface/src/MainWindow.cpp

@@ -24,7 +24,8 @@
 
 MainWindow::MainWindow(QWidget* parent) :
     QMainWindow(parent),
-    _windowGeometry("WindowGeometry")
+    _windowGeometry("WindowGeometry"),
+    _windowState("WindowState", 0)
 {
 }
 
@@ -34,13 +35,24 @@ void MainWindow::restoreGeometry() {
     QRect geometry = _windowGeometry.get(qApp->desktop()->availableGeometry());
     move(geometry.topLeft());
     resize(geometry.size());
+
+    // Restore to maximized or full screen after restoring to windowed so that going windowed goes to good position and sizes.
+    Qt::WindowStates state = _windowState.get(Qt::WindowNoState);
+    if (state != Qt::WindowNoState) {
+        setWindowState(state);
+    }
 }
 
 void MainWindow::saveGeometry() {
     // Did not use geometry() on purpose,
     // see http://doc.qt.io/qt-5/qsettings.html#restoring-the-state-of-a-gui-application
-    QRect geometry(pos(), size());
-    _windowGeometry.set(geometry);
+    _windowState.set(windowState());
+
+    // Save position and size only if windowed so that have good values for windowed after starting maximized or full screen.
+    if (windowState() == Qt::WindowNoState) {
+        QRect geometry(pos(), size());
+        _windowGeometry.set(geometry);
+    }
 }
 
 void MainWindow::moveEvent(QMoveEvent* event) {

interface/src/MainWindow.h

@@ -38,6 +38,7 @@ protected:
     
 private:
     Setting::Handle<QRect> _windowGeometry;
+    Setting::Handle<int> _windowState;
 };
 
 #endif /* defined(__hifi__MainWindow__) */