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 ( positions != null )
			{
				for ( int i = 0; i < array.length; i++ )
				{
					DesignElementHandle newObj = performInsert( array[i],
							positions[i],
							targetParent );
					if ( i == rule.getFocusIndex( ) )
					{
						result = newObj;
					}
					else
					{
						DNDUtil.addElementHandle( positions[i], newObj );
					}
				}
			}
		}
		else if ( array.length != 0 )
		{
			result = performInsert( array[0], target, targetParent );
		}
		return result;
	}
	protected static DataItemHandle performInsertParameter(
			ScalarParameterHandle model ) throws SemanticException
	{