Cannot move window because the title bar is above the screen

Hold down "Alt", left click and hold in the window, and then move the mouse around. That should grab the window and let you move it.

In Gnome 3, the default is to use the Super aka Window key with mouse drag. In many previous Ubuntu window managers, it was the Alt key with mouse drag. There are a variety of ways to change this keybinding. See How to enable dragging windows with alt-click in gnome 3 / gnome shell - Super User