Ubuntu 18: Top bar for all monitors

Solution 1:

You can use a Gnome Shell extension, such as Multi Monitors, to add the top bar on the second monitor.

If you're not familiar with installing Gnome Shell extensions, you may want to see this: How do I install and manage GNOME Shell extensions?

Solution 2:

For me the easiest option was to revert to the Unity desktop manager (which was standard before but then got replaced by GNOME in Ubuntu 18) using

$ sudo apt update
$ sudo apt install ubuntu-unity-desktop

Solution 3:

In the default GNOME window manager that comes with Ubuntu 18, you can move any window by holding down the Windows key while clicking on the window you want to move. Drag it to its' new position and you're done!

Note, in the Unity window manager, used before Ubuntu 17, you would hold down the Alt key instead.

I personally lament the absence of this feature every time I have to use Windows or a Mac.