Popup context menu.

def context_menu_requested(self, event):
        """Popup context menu."""
        if self.fig:
            pos = QPoint(event.x(), event.y())
            context_menu = QMenu(self)
            context_menu.addAction(ima.icon('editcopy'), "Copy Image",
                                   self.copy_figure,
                                   QKeySequence(
                                       get_shortcut('plots', 'copy')))
            context_menu.popup(self.mapToGlobal(pos))