The appearance and behavior of your X environment is controlled to a large degree by the window manager which you are running. The window manager affects the way title bars work, the pop-up menus displayed by clicking a mouse button in the root window (the screen ``background''), and other features relevant to the way windows are displayed and are manipulated on the screen.
Since most of our workstation use gdm, you have a choice of window managers as you like. It has at least three different session's setups. It has been configured for gnome, kde, and fvwm2. We're currently using gnome as our default session manager and sawfish as our default window manager for most of our workstation. Those are somewhat fairly sophisticated managers which allow multiple ``virtual'' desktops to increase your working surface on the screen.
Sometimes our default window manager give user a little problem which user can not move any window on a screen. To fix this problem, you can find a ToolBox icon in the bottom or top control panel. Click the ToolBox icon then click a window manager option. Then you can see few different options of window manager selection. If you want to keep sawfish as your default window manager, change your window manager to other window manager and change back.
The configuration of fvwm2 is controlled by the .fvwm2rc file in your home directory. The configurations of gnome are located a directory .gnome in your home directory.