This post shows how to use Drag and Drop library described in my previous post "Drag and drop table content with JavaScript". HTML table is stylized to have left column with content, main table and message line. Elements on the left side (green and orange) should be placed to the coloured table cells. After elements are correctly sited, appropriate message will be displayed.

Content of HTML table cells can be dragged to another table cell or another table. It isn't difficult to define onMouseMove handler and change top / left element styles to move the object. In case with tables, you will have to determine somehow destination table cell. Attaching onMouseOver handler on table cells will not work, because browser doesn't fire events to the elements beneath the dragged object.