QT: Various interface fixes (#2496)

* QT: Various interface fixes

* fix close without saving

* +

* +

using the save and close buttons, everything works fine, but when using the X button it doesn't work very well...

* fix close (X) without saving

src/qt_gui/settings_dialog.h

@@ -42,6 +42,7 @@ private:
     void InitializeEmulatorLanguages();
     void OnLanguageChanged(int index);
     void OnCursorStateChanged(s16 index);
+    void closeEvent(QCloseEvent* event) override;
 
     std::unique_ptr<Ui::SettingsDialog> ui;
 
@@ -50,4 +51,6 @@ private:
     QString defaultTextEdit;
 
     int initialHeight;
+
+    bool is_saving = false;
 };