Need help figuring out how to paint graphicsRectItems correctly

I am stuck with two versions of code that only differ in the way the rect is assigned. How are they different? and how does this effect the different behaviour?

(What I want is rectangles that are painted correctly with another style for selected ones and that can be moved around if in selection mode. I distinguish the mode in self.newItem. If True I am in adding-rectangles mode and if False I am in selection mode.)

This code below produces rectangles that are
- painted "correct" (snapped to grid)

- are selectable (but not drawn in red and yellow as in the paint method but with a black dashed line; although in debugging i see that the if-code for selected is visited)

- can be moved (snapped to grid)

Code:

class DesignerBlock(QGraphicsRectItem):
    def __init__(self, rect=QRectF(0, 0, 0, 0), parent=None, scene=None):
        super(DesignerBlock, self).__init__(parent, scene)
        self.setFlag(self.ItemIsMovable, True)
        self.setFlag(self.ItemIsSelectable, True)
        self.setFlag(self.ItemSendsGeometryChanges, True)
        self.setPen(QPen(Qt.black, 1, Qt.SolidLine))
        self.setBrush(QBrush(Qt.white, Qt.SolidPattern))
        self.moving = False
        self.setRect(rect) # <-----
        self.setSelected(True)
        self.setFocus()
        self.update()
 
    def paint(self, painter, option, widget):
        pen = self.pen()
        brush = self.brush()
        if self.isSelected():
            pen = QPen(Qt.red, 1, Qt.SolidLine)
            brush = QBrush(Qt.yellow, Qt.SolidPattern)
        painter.setPen(pen)
        painter.setBrush(brush)
        painter.drawRect(self.rect()) # <-----
        super(DesignerBlock, self).paint(painter, option, widget)
 
    def deferPosition(self, value):
        big = abs(value) / SCREEN_GRID
        little = abs(value) % SCREEN_GRID
 
        if little > (SCREEN_GRID / 2):
            little = 1
        else:
            little = 0
 
        if value > 0:
            direction = 1
        else:
            direction = -1
 
        return (big + little) * SCREEN_GRID * direction
 
 
    def itemChange(self, change, value):
        if change == QGraphicsItem.ItemPositionChange:
            x = value.toPoint().x()
            y = value.toPoint().y()
            newPosition = value.toPoint()
 
            newPosition.setX(self.deferPosition(x))
 
            newPosition.setY(self.deferPosition(y))
 
            return newPosition
        else:
            return value

Now this code below (the same except the two indicated changes) makes rectangles that
- are painted only in the rect of the mouse selection (but not adjusted to snap to grid)
with that i mean that if i rubberband a rect smaller than the grid point, only this area is painted although after i force a repaint (as in window minimize/maximize) the rectitem is drawn correct from gridPoint to gridPoint.

- selected rect is painted in red and yellow

- when selecting with rubberband the view is "erased" and click select does not work and they dont move

Code:

class DesignerBlock(QGraphicsRectItem):
    def __init__(self, rect=QRectF(0, 0, 0, 0), parent=None, scene=None):
        super(DesignerBlock, self).__init__(parent, scene)
        self.setFlag(self.ItemIsMovable, True)
        self.setFlag(self.ItemIsSelectable, True)
        self.setFlag(self.ItemSendsGeometryChanges, True)
        self.setPen(QPen(Qt.black, 1, Qt.SolidLine))
        self.setBrush(QBrush(Qt.white, Qt.SolidPattern))
        self.moving = False
        self.rect = rect # <----------
        #self.setRect(rect)
        self.setSelected(True)
        self.setFocus()
        self.update()
 
    def paint(self, painter, option, widget):
        pen = self.pen()
        brush = self.brush()
        if self.isSelected():
            pen = QPen(Qt.red, 1, Qt.SolidLine)
            brush = QBrush(Qt.yellow, Qt.SolidPattern)
        painter.setPen(pen)
        painter.setBrush(brush)
        painter.drawRect(self.rect) # <-----------
        #painter.drawRect(self.rect())
        super(DesignerBlock, self).paint(painter, option, widget)
 
    def deferPosition(self, value):
        big = abs(value) / SCREEN_GRID
        little = abs(value) % SCREEN_GRID
 
        if little > (SCREEN_GRID / 2):
            little = 1
        else:
            little = 0
 
        if value > 0:
            direction = 1
        else:
            direction = -1
 
        return (big + little) * SCREEN_GRID * direction
 
 
    def itemChange(self, change, value):
        if change == QGraphicsItem.ItemPositionChange:
            x = value.toPoint().x()
            y = value.toPoint().y()
            newPosition = value.toPoint()
 
            newPosition.setX(self.deferPosition(x))
 
            newPosition.setY(self.deferPosition(y))
 
            return newPosition
        else:
            return value

this is scene code for handling the mouse events:

Code:

def mousePressEvent(self, mouseEvent):
        self.startPos = mouseEvent.scenePos()
        self.emit(SIGNAL("startSet"), self.gridPos(self.startPos))
        if self.newItem == False:
            super(DesignerScene, self).mousePressEvent(mouseEvent) 
 
    def mouseMoveEvent(self, mouseEvent):
        self.emit(SIGNAL("updateCoords"), self.gridPos(mouseEvent.scenePos()))
        super(DesignerScene, self).mouseMoveEvent(mouseEvent) 
 
    def mouseReleaseEvent(self, mouseEvent):
        self.endPos = mouseEvent.scenePos()
        self.emit(SIGNAL("endSet"), self.gridPos(self.endPos))
        if self.newItem:
            self.emit(SIGNAL("createBox"), self.gridPos(self.startPos), self.gridPos(self.endPos))
        else:
            super(DesignerScene, self).mousePressEvent(mouseEvent) 
 
    def createBox(self, start, end):
        xs = start.x()
        ys =  start.y()
        xe =  end.x()
        ye =  end.y()
        if ys <> ye and xs <> xe:
            # insert only if not a line
            self.addItem(DesignerBlock(QRectF(xs, ys, xe-xs, ye-ys).normalized()))