Fixed loss of index page form values on 'more options' link click.

Restores the behavior introduced eleven years ago (see commit
479861a3cf) and lost by mistake 3 years
ago (see commit 617dd9c97b), when the
click handler started referencing a missing HTML id.

htroot/index.html

@@ -72,7 +72,7 @@
 	        #(searchaudio)#::<input type="radio" id="audio" name="contentdom" value="audio" #(check)#::checked="checked"#(/check)# />&nbsp;Audio&nbsp;&nbsp;#(/searchaudio)#
 	        #(searchvideo)#::<input type="radio" id="video" name="contentdom" value="video" #(check)#::checked="checked"#(/check)# />&nbsp;Video&nbsp;&nbsp;#(/searchvideo)#
 	        #(searchapp)#::<input type="radio" id="app" name="contentdom" value="app" #(check)#::checked="checked"#(/check)# />&nbsp;Applications#(/searchapp)#
-	        #(searchoptions)#&nbsp;&nbsp;<a href="index.html?searchoptions=1" onclick="this.href='index.html?searchoptions=1&amp;former='+document.getElementById('searchinput').search.value+'&amp;contentdom='+radioValue(document.getElementById('searchinput').contentdom)">more options...</a>::#(/searchoptions)#
+	        #(searchoptions)#&nbsp;&nbsp;<a href="index.html?searchoptions=1" onclick="this.href='index.html?searchoptions=1&amp;former='+document.getElementById('search').value+'&amp;contentdom='+radioValue(document.getElementById('searchform').contentdom);">more options...</a>::#(/searchoptions)#
         </div>
         #(/searchdomswitches)#
         <input type="hidden" name="nav" value="#[search.navigation]#" />