checkbox column (defaults to <tt>false</tt>).</div></td><td class="msource">CheckboxSelectionModel</td></tr><tr class="config-row expandable "><td class="micon"><a href="#expand" class="exi"> </a></td><td class="sig"><a id="Ext.grid.CheckboxSelectionModel-header"></a><b><a href="source/CheckboxSelectionModel.html#cfg-Ext.grid.CheckboxSelectionModel-header">header</a></b> : String<div class="mdesc"><div class="short">Any valid text or HTML fragment to display in the header cell for the
checkbox column. Defaults to:'&lt;div class="x...</div><div class="long">Any valid text or HTML fragment to display in the header cell for the
checkbox column. Defaults to:<pre><code><em>'<div class=<em>"x-grid3-hd-checker"</em>>&#160;</div>'</em></tt></code></pre>
checkbox column (defaults to <tt>false</tt>).</div></td><td class="msource">CheckboxSelectionModel</td></tr><tr class="config-row expandable "><td class="micon"><a href="#expand" class="exi"> </a></td><td class="sig"><a id="Ext.grid.CheckboxSelectionModel-header"></a><b><a href="source/CheckboxSelectionModel.html#cfg-Ext.grid.CheckboxSelectionModel-header">header</a></b> : String<div class="mdesc"><div class="short">Any valid text or HTML fragment to display in the header cell for the
checkbox column. Defaults to:'&lt;div class="x...</div><div class="long">Any valid text or HTML fragment to display in the header cell for the
checkbox column. Defaults to:<pre><code><em>'<div class=<em>"x-grid3-hd-checker"</em>>&#160;</div>'</em></tt></code></pre>