Redraw custom QGraphicsItem on QPushButton click

[qutron]

I've got lots of widgets grouped in different layouts on my main widget. One of them is QGraphicsView displaying custom QGraphicsItem. Everything works fine, but I need some additional functionality and I want to repaint custom QGraphicsItem on QPushButton click.
How can I do it?

[Lykurg]

Use signals and slots.

[qutron]

And what should I connect?
I am sure signal is QPushButton::clicked(). But what about slot?
EDIT: QGraphicsView::updateScene()?

[Lykurg]

No, you need to define your custom slot which changes the item you want. Qt can't know what you want.