dragContext.mode

I have 2 grids that I can drag and drop between. When one row that has a specific userdata is dragged from mygrid1 to mygrid2, I would like to change the mode to copy. In the documention I found this:
http://docs.dhtmlx.com/doku.php?id=dhtmlxgrid:control_drop which refers to the dragContext but have not been able to get it to work.

I have tried:

mygrid2.attachEvent("onDrop",function(sId,tId,dId,sObj,tObj,sCol,tCol){
		if (mygrid1.getUserData(sId,"pr")=="pr") {
                                      mygrid1.dragContext.mode="copy";
			mygrid2.setUserData(dId,"pr","pr");
			mygrid2.setRowColor(dId,"#dbe6dd");
			return true;
		}
	});

Has anyone had luck using the dragContext? Is there something I am missing? Do I need to have additional linked javascript files besides …/dhtmlxGrid/codebase/ext/dhtmlxgrid_drag.js?

You are changing drag and drop mode too late when row already added to target grid and removed from source grid. Try to use “onDrag” event instead like in provided tutorial.

I still had difficulties getting it to work with dragContext.mode but it works perfectly with enableMercyDrag(). Thank you for your help!

mygrid1.attachEvent("onBeforeDrag",function(id){
		if (mygrid1.getUserData(id,"mm")=="mm") {
			mygrid1.enableMercyDrag(true);
			return true
		} else {
			mygrid1.enableMercyDrag(false);
			return true;
		}
	});