Requests a close for the inputed tab item.

        :param      item | <XViewPanelItem>

def closeTab(self, item):
        """
        Requests a close for the inputed tab item.

        :param      item | <XViewPanelItem>
        """
        index = self.indexOf(item)
        if index != -1:
            self.tabCloseRequested.emit(index)