Register plugin in Spyder's main window

def register_plugin(self):
        """Register plugin in Spyder's main window"""
        self.redirect_stdio.connect(self.main.redirect_internalshell_stdio)
        self.main.console.shell.refresh.connect(self.refresh_plugin)
        iconsize = 24 
        self.toolbar.setIconSize(QSize(iconsize, iconsize))
        self.main.addToolBar(self.toolbar)