Both Perl and Java layers have been updated to generate appropriate HTML
ID's in list tags.

Sebastian,

you created these ID's on the <td> instead of on the <input>

for example <td id="column1_1" class="list-checkbox">

this should be on 

<input type="checkbox" value="1015128756" onclick="checkbox_clicked(this, 'target_systems')" name="items_selected"/>

one place this is true is under 

System Groups

select a group

Target Systems

HTML ID's created on <input> checkbox elements as well:

<td id="column1_1" ...> <input type="checkbox" .... id="select_1"> </td>