Bug 166015 Refactor designer actions to eclipse command framework
Eclipse command framework provide a more explicit way to manage UI actions contributions, we can take it's advantage to make our actions code more clean and maintainable.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dnd/InsertInLayoutUtil.java
if ( insertObj instanceof DataSetHandle )
		{
			return DataSetUIUtil.hasMetaData( (DataSetHandle) insertObj );
		}
		return insertObj instanceof ResultSetColumnHandle
				|| insertObj instanceof ScalarParameterHandle;
	}
	protected static void insertToCell( DataSetHandle model,
			TableHandle tableHandle, SlotHandle slot,
			ResultSetColumnHandle[] columns, boolean isLabel )
	{
		for ( int i = 0; i < slot.getCount( ); i++ )
		{
			SlotHandle cells = ( (RowHandle) slot.get( i ) ).getCells( );
			for ( int j = 0; j < cells.getCount( ); j++ )
			{
				CellHandle cell = (CellHandle) cells.get( j );
				try
				{
					if ( isLabel )
					{
						LabelHandle labelItemHandle = SessionHandleAdapter.getInstance( )
								.getReportDesignHandle( )
								.getElementFactory( )
								.newLabel( null );
						
						
						
						String labelText = getDisplayName( columns[j] );
						if ( labelText != null )