Dhtmlx tree disable node

how to disable a particular node in tree ,

Even if i set enable drag and drop scrolling to true it is not scrolling if i reach the end of that div portion… how to scroll it if the user wants to drop item to a node which is not visible in that div portion

how to disable a particular node in tree ,
    tree.lockItem(id,true);   // please beware that it will disable ALL operations against related item

>>Even if i set enable drag and drop scrolling to true it is not scrolling if i reach the end of that div portion
    Please be sure that DIV tag used as tree container has not “overflow:auto” or “overflow:scroll” style attached ( if such style attached the external scrollbar will be shown instead of inner one )
    Also, please beware that tree can control only  inner scroll, if you have some outer containers with scrollbars - their state will not be changed