Xrandr is used to set the size, orientation and/or reflection of the outputs for a screen. It can also set the screen size. A
ArandR is a visual front end for XRandR 1.2 (per display options), which provides full control over positioning, saving and loading to/from shell scripts and easy integration with other applications.
The xprop utility is for displaying window and font properties in an X server. One window or font is selected using the command line arguments or possibly in the case of a window, by clicking on the desired window. A list of properties is then given, possibly with formatting information.
xev - print contents of X events.
