'Draw the fold indicator/trigger (arrow).
:param top: Top position
:param mouse_over: Whether the mouse is over the indicator
:param collapsed: Whether the trigger is collapsed or not.
:param painter: QPainter'

def _draw_fold_indicator(self, top, mouse_over, collapsed, painter):

    rect = QRect(0, top, self.sizeHint().width(), self.sizeHint().height())
    if self._native_icons:
        opt = QStyleOptionViewItem()
        opt.rect = rect
        opt.state = ((QStyle.State_Active | QStyle.State_Item) | QStyle.State_Children)
        if (not collapsed):
            opt.state |= QStyle.State_Open
        if mouse_over:
            opt.state |= ((QStyle.State_MouseOver | QStyle.State_Enabled) | QStyle.State_Selected)
            opt.palette.setBrush(QPalette.Window, self.palette().highlight())
        opt.rect.translate((-2), 0)
        self.style().drawPrimitive(QStyle.PE_IndicatorBranch, opt, painter, self)
    else:
        index = 0
        if (not collapsed):
            index = 2
        if mouse_over:
            index += 1
        ima.icon(self._indicators_icons[index]).paint(painter, rect)
