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<info>
<link type="next" xref="tour-get_object"/>
<revision version="0.1" date="2013-06-17" status="stub"/>
<credit type="author copyright">
<name>Ekaterina Gerasimova</name>
<email its:translate="no">kittykat3756@gmail.com</email>
<years>2013</years>
</credit>
<credit type="author copyright">
<name>Gordon Hill</name>
<email its:translate="no">caseyweederman@gmail.com</email>
<years>2013</years>
</credit>
<include xmlns="http://www.w3.org/2001/XInclude" href="cc-by-sa-3-0.xml"/>
<desc>Bind functions to events using Lang.</desc>
</info>
<title>Actions and signals</title>
<links type="prevnext" style="top"/>
<links type="series" style="floatend">
<title>Get started with GNOME</title>
</links>
<p>Gtk has a set of predefined events that you can use in your application.</p>
<example>
<p>Declare <code>HelloWorld</code> as a new class.</p>
<code><![CDATA[
class HelloWorld {
]]></code>
<p><code>constructor</code> is called when a new instance is created. Create a
<code>GtkApplication</code>, then connect <code>activate</code> to the
existing Gtk event <code>_onActivate</code> and <code>startup</code> to
<code>_onStartup</code>:</p>
<code><![CDATA[
constructor() {
this.application = new Gtk.Application();
this.application.connect('activate', this._onActivate.bind(this));
this.application.connect('startup', this._onStartup.bind(this));
}
]]></code>
<p>Show the window upon application activation:</p>
<code><![CDATA[
_onActivate() {
this._window.show_all();
}
]]></code>
</example>
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