In bellow given example, "openWindow" command will open "https://www.yahoo.com" in new browser tab. Please note, it firefox has blocked popup window then selenium IDE software testing tool will show you error. In this case please allow browser to open popups.
- See more at: http://software-testing-tutorials-automation.blogspot.com/2012/10/selenium-ide-openand-openwindow-command.html#sthash.RNzlR4Pm.dpuf