Binary package “wininfo” in ubuntu disco

dynamic window information viewer

 This package provides a window information utility for developers of
 applications, toolkits, and window managers. wininfo follows your
 pointer providing information about the windows below. The information
 presented includes:
  - a detailed description of the window hierarchy below the pointer;
  - parsed interpretations of standard properties from both the
    application window and the window manager;
  - information about X server resources used by the application.