I want to set my gnome calculator in programming mode to do some hex calculations but there is no menu bar visible on the gcaltool app.
If you wish to change anything for an application, you will need to hover over the top task bar while focusing on the application.
This style for the menus reminds me of a Mac which has the same mentality. Picture below to see what I am talking about with the steps above.
This works in these versions of Ubuntu (if you are using Unity):
Hope this helps.