I would like to have my screen fully powered at all times, but it goes to standby once I lock my PC.
Open your System Settings. We need to make changes to Power and Brightness & Lock settings.
Change the value of Suspend when inactive for to Don't suspend.
Brightness & Lock Settings
Change the value of Turn screen off when inactive for to Never.
This should help to achieve your desired result.
Ny problem is that I am using Ubuntu 15.10 with gnome-session-flashback installed and using the Metacity interface. This is one of the few things not shown in the Menus. I need to add it to the menu or know how to do it from the command line. Use to have this stuff as well under 14.04 LTS. Can you help me?
By the way, Main Menu will let you change what shows up and where, but to add something, you keed to know the command line call. How do I find out what I have and where it shows up in the menus if it shows up at all? Some show up in multiple places, often with different icons. It could be better.