Thats the menu aka "settings overflow" button, thats left android from 3.0 onward.
see:
https://android-developers.googleblo...nu-button.html
You could use an app like this one:
https://play.google.com/store/apps/d...ast.menubutton , and in general, if you find an app that has this command built in as an "activity", you can chain gesture control to execute that action. I havent checked if thats possible with this app, but cycle through a few of them, one eventually has to give you that option.