I use a treeview Control plugin ( server side) which reproduce me this :
<link rel="stylesheet" href="http://localhost/Web_Erp/obout/tree2/style/Classic/obout_treeview2.css" />
<script type="text/javascript" language="JavaScript">var ob_tree_id="tree1";verdadero=true;falso=false;wahr=true;falsch=false;vrai=true;faux=false;var ob_icons="http://localhost/Web_Erp/obout/tree2/icons";var ob_style="http://localhost/Web_Erp/obout/tree2/style/Classic";ob_tree_dnd_enable=false;ob_tree_editnode_enable=false;ob_tree_keynav_enable=false;ob_tree_multiselect_enable=false;ob_expand_single=false;ob_t2_showicons=true;</script><script language="JavaScript" type="text/javascript" src="http://localhost/Web_Erp/obout/tree2/script/ob_tree_2032.js"></script><script language="JavaScript" type="text/javascript" src="http://localhost/Web_Erp/obout/tree2/script/ob_events_2032.js"></script>
<div id="tree1" class="ob_tree" style="overflow:visible;"><div class="ob_di2"><div class="ob_d2b"><table class="ob_t2b" cellspacing="0" style="display:block;"><tr><td class="ob_t8"><img alt="" src="http://localhost/Web_Erp/obout/tree2/style/Classic/minus_r.gif" onclick="ob_t21(this, '')" /></td><td class="ob_t4"><div class="ob_d4"><img alt="" src="http://localhost/Web_Erp/obout/tree2/icons/Folder.gif"
(sorry for long text but it was just to show you different sections.)
this is being generated in ASHX ( and injected to client via jQuery).
what is the right contentType for that kind of output ?
context.Response.ContentType=???
context.Response.ContentType = "text/html";