/usr/share/doc/python-gtk2-tutorial/html/sec-SignalEmissionAndPropagation.html is in python-gtk2-tutorial 2.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>20.2. Signal Emission and Propagation</title><meta name="generator" content="DocBook XSL Stylesheets V1.65.1"><link rel="home" href="index.html" title="PyGTK 2.0 Tutorial"><link rel="up" href="ch-AdvancedEventAndSignalHandling.html" title="Chapter 20. Advanced Event and Signal Handling"><link rel="previous" href="ch-AdvancedEventAndSignalHandling.html" title="Chapter 20. Advanced Event and Signal Handling"><link rel="next" href="ch-ManagingSelections.html" title="Chapter 21. Managing Selections"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">20.2. Signal Emission and Propagation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch-AdvancedEventAndSignalHandling.html">Prev</a> </td><th width="60%" align="center">Chapter 20. Advanced Event and Signal Handling</th><td width="20%" align="right"> <a accesskey="n" href="ch-ManagingSelections.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec-SignalEmissionAndPropagation"></a>20.2. Signal Emission and Propagation</h2></div></div><div></div></div><p>Signal emission is the process whereby GTK+ runs all handlers for
a specific object and signal.</p><p>First, note that the return value from a signal emission is the
return value of the last handler executed. Since event signals are all of
type <tt class="literal">RUN_LAST</tt>, this will be the default (GTK+ supplied)
handler, unless you connect with the
<tt class="methodname">connect_after</tt>() method.</p><p>The way an event (say "button_press_event") is handled,
is:</p><div class="itemizedlist"><ul type="disc"><li><p>Start with the widget where the event occurred.</p></li><li><p>Emit the generic "event" signal. If that signal handler
returns a value of <tt class="literal">TRUE</tt>, stop all processing.</p></li><li><p>Otherwise, emit a specific, "button_press_event" signal. If
that returns <tt class="literal">TRUE</tt>, stop all processing.</p></li><li><p>Otherwise, go to the widget's parent, and repeat the above
two steps.</p></li><li><p>Continue until some signal handler returns
<tt class="literal">TRUE</tt>, or until the top-level widget is reached.</p></li></ul></div><p>Some consequences of the above are:</p><div class="itemizedlist"><ul type="disc"><li><p>Your handler's return value will have no effect if there is
a default handler, unless you connect with
<tt class="methodname">connect_after</tt>().</p></li><li><p>To prevent the default handler from being run, you need to
connect with <tt class="methodname">connect</tt>() and use
<tt class="methodname">emit_stop_by_name</tt>() - the return value only affects
whether the signal is propagated, not the current emission.</p></li></ul></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch-AdvancedEventAndSignalHandling.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch-AdvancedEventAndSignalHandling.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch-ManagingSelections.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 20. Advanced Event and Signal Handling </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 21. Managing Selections</td></tr></table></div></body></html>
|