After installation of Fedora Core 12, I couldn’t find option “focus window on mouse over”. In previous Fedora, there was Window Preferences in GNOME with following options: Window Selection, Titlebar Action and Movement Key. The solution was to install control-center-extra package.
First check if you have Windows option in Fedora Core 12 (just to be sure what’s missing).
System -> Preferences -> Windows
If not you can’t find Windows option, install the following package:
yum install control-center-extra
Package size is 59KB. After installation, Windows option should appear and you will be able to set roll-up window or select windows when the mouse moves over. Small but useful tip – I hope.