Required library edition:
Required library file: dhtmlxfolders.js

clears all filters. Set parameter to true if you'd like to call some method next to it, which will redraw contnet any way.

    <script>
       function filterFolders(val){
         if(this.value==''){
           myFolders.filterClear()
         }else{
           myFolders.filterItems(function(item,mask){
              if(item.data.dataObj.getAttribute("name").indexOf(val)!=-1)
                 true;
              else
                 false;
           },val,false);
         }
       }
    </script>
    <input type="text" onblur="filterFolders(this.value)">