<HTML ><HEAD ><TITLE >Window Manager Protocols</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.72 "><LINK REL="HOME" HREF="index.html"><LINK REL="PREVIOUS" TITLE="Application Window Properties" HREF="x225.html"><LINK REL="NEXT" TITLE="Implementation notes" HREF="x351.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x225.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x351.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="AEN340" >6. Window Manager Protocols</A ></H1 ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN342" >6.1. _NET_WM_PING</A ></H2 ><P >This protocol allows the Window Manager to determine if the Client is still processing X events. This can be used by the Window Manager to determine if a window which fails to close after being sent WM_DELETE_WINDOW has stopped responding, or has stalled for some other reason, such as waiting for user confirmation. A Client SHOULD indicate that it is willing to participate in this protocol by listing _NET_WM_PING in the WM_PROTOCOLS property of the client window. </P ><P >A Window Manager can use this protocol at any time by sending a client message as follows: </P ><PRE CLASS="PROGRAMLISTING" >type = ClientMessage window = the respective client window message_type = WM_PROTOCOLS format = 32 data.l[0] = _NET_WM_PING data.l[1] = timestamp</PRE ><P >A participating Client receiving this message MUST send it back to the root window immediately, by setting window = root, and calling XSendEvent. The Client MUST NOT alter the timestamp, as this can be used by the Window Manager to uniquely identify the ping. </P ><P >The Window Manager MAY kill the Client (using _NET_WM_PID) if it fails to respond to this protocol within a reasonable time. </P ><P >See also the implementation notes on <A HREF="x351.html#KILLINGWINDOWS" >killing hung processes</A >. </P ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x225.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x351.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Application Window Properties</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" > </TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Implementation notes</TD ></TR ></TABLE ></DIV ></BODY ></HTML >