Added some more hooks to the page editing pipeline. It should now be possible to add controls to the page editor, send the data from them out to the server, and process them on the server side.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>{#xhtmlxtras_dlg.title_ins_element}</title>
<script type="text/javascript" src="../../tiny_mce_popup.js"></script>
<script type="text/javascript" src="../../utils/mctabs.js"></script>
<script type="text/javascript" src="../../utils/form_utils.js"></script>
<script type="text/javascript" src="../../utils/editable_selects.js"></script>
<script type="text/javascript" src="js/element_common.js"></script>
<script type="text/javascript" src="js/ins.js"></script>
<link rel="stylesheet" type="text/css" href="css/popup.css" />
</head>
<body id="xhtmlxtrasins" style="display: none">
<form onsubmit="insertIns();return false;" action="#">
<div class="tabs">
<ul>
<li id="general_tab" class="current"><span><a href="javascript:mcTabs.displayTab('general_tab','general_panel');" onmousedown="return false;">{#xhtmlxtras_dlg.general_tab}</a></span></li>
<!-- <li id="events_tab"><span><a href="javascript:mcTabs.displayTab('events_tab','events_panel');" onmousedown="return false;">{#xhtmlxtras_dlg.events_tab}</a></span></li> -->
</ul>
</div>
<div class="panel_wrapper">
<div id="general_panel" class="panel current">
<fieldset>
<legend>{#xhtmlxtras_dlg.fieldset_general_tab}</legend>
<table border="0" cellpadding="0" cellspacing="4">
<tr>
<td class="label"><label id="datetimelabel" for="datetime">{#xhtmlxtras_dlg.attribute_label_datetime}</label>:</td>
<td>
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td><input id="datetime" name="datetime" type="text" value="" maxlength="19" class="field mceFocus" /></td>
<td><a href="javascript:insertDateTime('datetime');" onmousedown="return false;" class="browse"><span class="datetime" title="{#xhtmlxtras_dlg.insert_date}"></span></a></td>
</tr>
</table>
</td>
</tr>
<tr>
<td class="label"><label id="citelabel" for="cite">{#xhtmlxtras_dlg.attribute_label_cite}</label>:</td>
<td><input id="cite" name="cite" type="text" value="" class="field" /></td>
</tr>
</table>
</fieldset>
<fieldset>
<legend>{#xhtmlxtras_dlg.fieldset_attrib_tab}</legend>
<table border="0" cellpadding="0" cellspacing="4">
<tr>
<td class="label"><label id="titlelabel" for="title">{#xhtmlxtras_dlg.attribute_label_title}</label>:</td>
<td><input id="title" name="title" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label id="idlabel" for="id">{#xhtmlxtras_dlg.attribute_label_id}</label>:</td>
<td><input id="id" name="id" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label id="classlabel" for="class">{#xhtmlxtras_dlg.attribute_label_class}</label>:</td>
<td>
<select id="class" name="class" class="field mceEditableSelect">
<option value="">{#not_set}</option>
</select>
</td>
</tr>
<tr>
<td class="label"><label id="stylelabel" for="class">{#xhtmlxtras_dlg.attribute_label_style}</label>:</td>
<td><input id="style" name="style" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label id="dirlabel" for="dir">{#xhtmlxtras_dlg.attribute_label_langdir}</label>:</td>
<td>
<select id="dir" name="dir" class="field">
<option value="">{#not_set}</option>
<option value="ltr">{#xhtmlxtras_dlg.attribute_option_ltr}</option>
<option value="rtl">{#xhtmlxtras_dlg.attribute_option_rtl}</option>
</select>
</td>
</tr>
<tr>
<td class="label"><label id="langlabel" for="lang">{#xhtmlxtras_dlg.attribute_label_langcode}</label>:</td>
<td>
<input id="lang" name="lang" type="text" value="" class="field" />
</td>
</tr>
</table>
</fieldset>
</div>
<div id="events_panel" class="panel">
<fieldset>
<legend>{#xhtmlxtras_dlg.fieldset_events_tab}</legend>
<table border="0" cellpadding="0" cellspacing="4">
<tr>
<td class="label"><label for="onfocus">onfocus</label>:</td>
<td><input id="onfocus" name="onfocus" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onblur">onblur</label>:</td>
<td><input id="onblur" name="onblur" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onclick">onclick</label>:</td>
<td><input id="onclick" name="onclick" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="ondblclick">ondblclick</label>:</td>
<td><input id="ondblclick" name="ondblclick" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onmousedown">onmousedown</label>:</td>
<td><input id="onmousedown" name="onmousedown" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onmouseup">onmouseup</label>:</td>
<td><input id="onmouseup" name="onmouseup" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onmouseover">onmouseover</label>:</td>
<td><input id="onmouseover" name="onmouseover" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onmousemove">onmousemove</label>:</td>
<td><input id="onmousemove" name="onmousemove" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onmouseout">onmouseout</label>:</td>
<td><input id="onmouseout" name="onmouseout" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onkeypress">onkeypress</label>:</td>
<td><input id="onkeypress" name="onkeypress" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onkeydown">onkeydown</label>:</td>
<td><input id="onkeydown" name="onkeydown" type="text" value="" class="field" /></td>
</tr>
<tr>
<td class="label"><label for="onkeyup">onkeyup</label>:</td>
<td><input id="onkeyup" name="onkeyup" type="text" value="" class="field" /></td>
</tr>
</table>
</fieldset>
</div>
</div>
<div class="mceActionPanel">
<div style="float: left">
<input type="submit" id="insert" name="insert" value="{#update}" />
</div>
<div style="float: left">
<input type="button" id="remove" name="remove" class="button" value="{#xhtmlxtras_dlg.remove}" onclick="removeIns();" style="display: none;" />
</div>
<div style="float: right">
<input type="button" id="cancel" name="cancel" value="{#cancel}" onclick="tinyMCEPopup.close();" />
</div>
</div>
</form>
</body>
</html>