feat: Prevent Tab key from moving focus outside active viewport tools

src/MainWindow.h

@@ -3,6 +3,7 @@
 
 #include <QMainWindow>
 
+class QEvent;
 class ViewportWidget;
 class Document;
 class Feature;
@@ -29,6 +30,9 @@ private slots:
     void exitSketchMode();
     void updateWindowTitle(const QString& filePath);
 
+protected:
+    bool eventFilter(QObject *watched, QEvent *event) override;
+
 private:
     ApplicationController* m_appController;
     ViewportWidget *m_viewport;