Required library edition:
Required library file: dhtmlxgrid_drag.js

redefine this method in your code to define how grid row values should be used in another grid

• rowId - id of draged row
• sgrid - source grid object
• tgrid - target grid object

Returns array of values for cells in target grid row

 grid.gridToGrid = function(rowId,sgrid,tgrid){
            var z=[];
            for (var i=0; i<sgrid.getColumCount(); i++)    // for each cell in the source grid
                z[i]=sgrid.cells(rowId,i).getValue();         // prepare data for the target grid
            return z;
        }

See also: gridToTreeElement