How To Make A QGraphics Item Double clickable? (total newbie)

[Gregarious]

#include "dialog.h"
#include "ui_dialog.h"
#include <QGraphicsRectItem>

Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);

scene = new QGraphicsScene;

ui->graphicsView->setScene(scene);

QBrush blueBrush(Qt::blue);

QPen blackPen(Qt::black);

blackPen.setWidth(6);

rectangle = scene->addRect(-100, -100, 50, 50, blackPen, blueBrush );

rectangle->setFlag(QGraphicsRectItem::ItemIsMovable);

// I'd like to connect a double click on my rectangle to a function, but don't have a CLUE how!
//

// some connect function here: doubleclick on rectangle calls open_modal

}

void Dialog::open_modal()
{

//do stuff

}