XQueryTree - query window tree information

children_return
                 Returns the list of children.

       display   Specifies the connection to the X server.

       nchildren_return
                 Returns the number of children.

       parent_return
                 Returns the parent window.

       root_return
                 Returns the root window.

       w         Specifies the window whose list of children, root, parent, and number of children you  want  to
                 obtain.

       This really should return a screen *, not a root window ID.

       The  XQueryTree  function  returns  the  root ID, the parent window ID, a pointer to the list of children
       windows (NULL when there are no children), and the number of children  in  the  list  for  the  specified
       window.   The children are listed in current stacking order, from bottom-most (first) to top-most (last).
       XQueryTree returns zero if it fails and nonzero if it succeeds.  To free a non-NULL children list when it
       is no longer needed, use XFree.

       XQueryTree can generate a BadWindow error.

BadWindow A value for a Window argument does not name a defined Window.

       XQueryTree - query window tree information

XFree(3), XGetWindowAttributes(3), XQueryPointer(3)
       Xlib-CLanguageXInterface

X Version 11                                      libX11 1.8.12                                    XQueryTree(3)

       Status  XQueryTree(Display  *display,  Window  w,  Window  *root_return,  Window  *parent_return,  Window
              **children_return, unsigned int *nchildren_return);