Drag and Drop Datagrid - Source and target grid id's or something

[graveytrain]

I have 4 simple tables, and when I drag and drop to one another everything works just fine.  I would like to be able to have table A drag drop to table C, but not be able to drop in table B and D.  and B and D drag drop but not from or to  A or C.  The source is just the row data, so that isn't helping me. anyone implemented something similar want to share the secret.

What I envisioned was to have A start drag and drop and then when drag enter on B return false or something to not allow the drop and then when it enters C it would drag enter and accept and allow the drop.

Also I don't know if it is a bug, but I have to add empty rows to a grid in order for it to accept a drop, figured it would just accept the row if it was in the right format. Seemed strange concept.