xev - print contents of X events

       Jim Fulton, MIT X Consortium

X Version 11                                        xev 1.2.6                                             XEV(1)

Xev creates a window and then asks the X server to send it events whenever anything happens to the window
       (such as it being moved, resized, typed in, clicked in, etc.).  You can also attach  it  to  an  existing
       window.   It  is  useful  for seeing what causes events to occur and to display the information that they
       contain; it is essentially a debugging and development tool, and should not be needed in normal usage.

       xev - print contents of X events

-displaydisplay
               This option specifies the X server to contact.

       -geometrygeom
               This option specifies the size and/or location of the window, if a window is to be created.

       -bwpixels
               This option specifies the border width for the window.

       -bs{NotUseful,WhenMapped,Always}
               This option specifies what kind of backing store to give the window.  The default  is  NotUseful.
               Backing  store refers to the the pixels saved off-screen when the X server maintains the contents
               of a window; NotUseful means that the xev process will redraw its contents itself, as necessary.

       -idwindowid
               This option specifies that the window with the given id should be monitored, instead of  creating
               a new window.

       -root   This option specifies that the root window should be monitored, instead of creating a new window.

       -s      This  option  specifies that save-unders should be enabled on the window. Save unders are similar
               to backing store, but they refer rather to the saving  of  pixels  off-screen  when  the  current
               window  obscures  other  windows.  Save  unders are only advisory, and are normally set for popup
               dialogs and other transient windows.

       -namestring
               This option specifies the name to assign to the created window.

       -rv     This option specifies that the window should be in reverse video.

       -eventevent_mask
               Select which events to display.  The -event option can be  specified  multiple  times  to  select
               multiple  types  of events.  When not specified, all events are selected.  Available event masks:
               keyboard mouse expose visibility structure substructure focus property colormap owner_grab_button
               randr button

       -version
               This option prints the program version and exits.

X(7), xwininfo(1), xdpyinfo(1), Xlib Programmers Manual, X Protocol Specification

xev  [-display  displayname]  [-geometry  geom]  [-bw  pixels]  [-bs  {NotUseful,WhenMapped,Always}] [-id
       windowid] [-root] [-s] [-name string] [-rv] [-version] [-event event_mask [-event event_mask ...]]