Flickering of the trajectory overlay

It can occur that the trajectory overlay isn't drawn for a single frame, causing flickering. Other overlays, like the coordinate system, are drawn.

added GUI bug medium labels

This may be due to the drawing call being non-blocking. Maybe replacing this

            getScene()->update(); // repaint();
            qApp->processEvents();

with this

#include <QGraphicsView> 
QGraphicsView *view = scene()->views().first();
view->viewport()->repaint();

solves the problem?

created branch 247-flickering-of-the-trajectory-overlay to address this issue

mentioned in merge request !265 (merged)

mentioned in commit 33e61d54

closed with merge request !265 (merged)