Bug 313297 XML data set fail in chart data preview
chart/org.eclipse.birt.chart.ui/src/org/eclipse/birt/chart/ui/swt/CustomPreviewTable.java
protected void addDragListenerToHeaderButton( Button button )
	{
		DragSource ds = new DragSource( button, DND.DROP_COPY );
		ds.setTransfer( new Transfer[]{
			SimpleTextTransfer.getInstance( )
		} );
		CustomPreviewTableDragListener dragSourceAdapter = new CustomPreviewTableDragListener( this,
				button.getText( ) );
		ds.addDragListener( dragSourceAdapter );
	}
	Point getTableSize( )
	{
		return getSize( );
	}
	public void addEntry( String sText, int iIndex )
			throws IllegalArgumentException
	{
		if ( fHeadings == null || iIndex >= fHeadings.size( ) )
		{
			throw new IllegalArgumentException( Messages.getString( "CustomPreviewTable.Exception.InvalidColumnIndexNotDefined", String.valueOf( iIndex ) ) ); 
		}
		this.cnvCells.addEntry( sText, iIndex );