Program of the week xwininfo - window information utility for X
Run it via the command line and click on a window you’d like more information about, and view the output.
For more inforamtion see ‘man xwininfo’
osaka@OsakaPad ~ $ xwininfo xwininfo: Please select the window about which you would like information by clicking the mouse in that window. xwininfo: Window id: 0x201484c "Terminal" Absolute upper-left X: 684 Absolute upper-left Y: 54 Relative upper-left X: 1 Relative upper-left Y: 29 Width: 682 Height: 688 Depth: 32 Visual: 0x63 Visual Class: TrueColor Border width: 0 Class: InputOutput Colormap: 0x2000005 (not installed) Bit Gravity State: NorthWestGravity Window Gravity State: NorthWestGravity Backing Store State: NotUseful Save Under State: no Map State: IsViewable Override Redirect State: no Corners: +684+54 -0+54 -0-26 +684-26 -geometry 75x38-0+25