How to call the 1C-Bitrix modal admin window?

Question

1C-Bitrix

During the execution of the task, it was necessary to call a pop-up window from the admin panel to select a category on the user side, under administrator rights, similar to what is on the screen:
Maybe someone faced a similar task? Once a category is selected, its value must be stored in the input field.

Answer 1

I once put off how it works (there was such a task)

подгрузить данные из соседнего окна
1 окно 
<div class="small_button" onclick="jsUtils.OpenWindow('<?=$pt?>?n=komy_f', 500, 600);">Кому...</div>
<input type="text" name="komy_f" id="komy_f" value="" />
2 окно
<script type="text/javascript">
function SetEl(id, name){
  el = window.opener.document.getElementById('<?=$_REQUEST['n']?>');
  el.value = id;
  window.close();
}
</script>
<a href="#"  onclick="javascript:SetEl(\''.$value["EMAIL"].'\')">Select</a>