f20 - can't move windows

[Robert Moskowitz]

On f17 I can move a window or dialog box by holding down <alt> and <left 
mouse> and moving the window where I want.  This is very valuable on 
reduced screen devices where fixed dialogs don't fix all on the screen.

I cannot get this to work on f20.

I recall some mention somewhere in the installation instructions that a 
minimum of 800x640 was required for install, but that reduce screen 
sizes were supported after install.

How do I enable this feature?