The whole thing spans across all Screens and just displays a screenshot of all screens in the QPixmap.

This is my constructor:

// These are in the initializer list
auto scene = new QGraphicsScene;
auto view = new QGraphicsView(scene, this);

// Gets a Screenshot of all screens
scene->addPixmap(Screenshot::getScreenshotFull());

view->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view->show();

setCentralWidget(view);

Now once this window gets displayed, the Screenshot is moved to the right and down by about one pixel. (Which means there is a white border at the left and top screen)

How it should be:

How it actually is (I've made the top border red, left border white):

It seems like the QGraphicsScene indents all contents by one pixel so it is "visually inside" the outer widget/container (QGraphicsView)

Is there any way to get around this and remove that border?

When I used a QLabel and set the Pixmap via that, there was no border. I moved to the QGraphicsView because apparently that one is better if I want to draw plenty of rectangles onto it later on.. is that correct?

This whole thing is a Screenshot tool, so only an overlay where the user can crop out a rectangle (and also I can highlight windows with rectangles), is it a good idea for that to use a QMainWindow and by code only or should I use .ui files? Also is QGraphicsView the right option here? I want to draw a rectangle whenever the user hovers over certain areas.

Thanks.