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/editors/schematic/actions/AddStyleAction.java
StyleHandle styleHandle = DesignElementFactory.getInstance( reportDesignHandle )
				.newStyle( null );
		try
		{
			StyleBuilder dialog = new StyleBuilder( PlatformUI.getWorkbench( )
					.getDisplay( )
					.getActiveShell( ), styleHandle, StyleBuilder.DLG_TITLE_NEW );
			if ( dialog.open( ) == Window.OK )
			{
				if ( themeHandle != null )
				{
					themeHandle.getStyles( ).add( styleHandle );
				}
				else
				{
					reportDesignHandle.getStyles( ).add( styleHandle );
				}
				if ( !styleHandle.isPredefined( ) )
				{
					applyStyle( (SharedStyleHandle) styleHandle );
				}
				stack.commit( );
			}
		}
		catch ( Exception e )
		{
			stack.rollbackAll( );
			ExceptionHandler.handle( e );
		}