Plone 6 Remote Sprint - April 2020

Tips for remote sprinting and a report on improvements to the default theme, Volto, new training materials and more

A Successful Remote Sprint

Last week we held the first Plone remote sprint in the time of the coronavirus pandemic. It was a positive experience and a lot got done! Sprint plans and results were captured on the plone-6-sprint Etherpad and some chatting occurred on the plone/sprint Gitter channel. But the main method of communication was by video. Participants stayed connected by video all day, either on Jitsi or Discord. Each team had their own "room", and it was nice to be able to see everyone while working, even when microphones were muted. This mimicked the sort of frictionless in-person conversations that are the hallmark of sprints.

Sprint Topics

The sprinters tackled six different topics, here are the final reports on each. For more detailed information, see the plone-6-sprint Etherpad.

Modernize Plone's Default Theme

Peter Holzer and Stefan Antonelli led the charge with help from Robert Kuzma, plus Peter Mathis taking the lead on z3c.form. The team made a long list of contributions toward the following PLIPs:

Their work changes the default theme plonetheme.barceloneta to be based on Bootstrap 4 and SCSS. Plone specific styles have only been added where Bootstrap is lacking definitions for Plone elements. There is an overrides directory where all template overrides will be collected until they are merged back into the original packages.

Markup in general was improved. main_template markup was updated and the structure cleaned up, empty and unneeded elements have been removed. Header, navigation, portlets, status messages, batching - all markup and nav styles were updated. The generic view for content types was updated (this includes title, description, byline, related items and keywords). control_panel_overview, control_panel default, and some control panels with custom views were all updated.

For forms, Bootstrap markup was added to to give widgets and fields (buttons, input fields, etc.) a basic styling. Plone's classic backend forms are also fully functional as long as Bootstrap's default CSS is independently available. In fact a theme (e.g. Barceloneta) is not necessary as long as Bootstrap CSS is available.

Icons also got some love. icon_expr for actions, content types, etc. was reused to define SVG icons. bootstrap-icons were added as an available icon resource to plone.staticresources. The team selected and added icons to the control panel settings in the controlpanel.xml in plonetheme.barceloneta.

Mosaic was changed to use Flex for columns based on the updated Barceloneta theme. All LESS files were replaced with SCSS and 'npm run watch' is now used to compile the SCSS files. Redundant CSS classes were cleaned up and the default column limit was set to 6 columns. A reset button was added to Mosaic cells to reset to the automatic column width, and an automatic reset was added for column widths if a new column gets inserted. A label was added to indicate the current column width, with "0" for auto width.

A demo of classic Plone 5.2 with the latest Barceloneta default theme is at The Coredev buildout including the current state of work on the PLIP for Bootstrap 4 markup is at

The team plans to meet regularly to continue working every Wednesday at 5 PM CEST starting on May 13. They will meet in the plone-6-sprint-barceloneta Jitsi room. Everyone is welcome to join!

Simplify Resource Registry

Maik Derstappen led this project, in coordination with the Barceloneta work. They added a custom.css view, which renders the custom CSS added in the Theming Control Panel, after all other CSS resources are loaded. This allows you to override CSS coming from a Diazo theme.

The team also discussed what really needs to change in the Resource Registry. They decided to remove the build-button from the theming editor because it will not work with SCSS (which is now used by Barceloneta).

Developers should register resources already compiled as Resource Bundles with TTW compiling disabled. They can use the merge flag to merge it with default or logged-in bundles, but this only makes sense if they are always needed. Otherwise the resource can be disabled and loaded on demand via Python in the view/viewlet or by adding the header lines directly into the templates.

Variables can be defined as CSS variables. Variables from the registry are no longer used in SCSS/CSS in plonetheme.barceloneta.

Push Plone to Zope 5

Jens Klein reports that lots of "boring but important work" was done by Maurits van Rees including cleanup of package metadata and releases of packages. Jens Vagelpohl released Zope 5.0a2 and Jens Klein created a zope-5 branch for Plone 6.0 on buildout.coredev. Version dependencies were updated on this branch, and version pins that are orphaned or handled upstream by Zope were removed. Version dependencies still outstanding:

  • z3c.form - this will be handled later
  • Update Pillow from 6 latest to 7.x - check is needed on separate branch, this applies to the Plone 5.2 branch as well
  • Parts of the Robotframework test environment - due to non backward compatible changes in Selenium, and possibly other issues
  • Unicode Encode/Decode  - this one has been open for a long time and Jens would like to see some fellow Plonista take the challenge to update or get rid of it!
  • Cleanup of any orphaned dependencies - for some packages it is difficult to know were they are used, especially for dependencies of our ecosystem packages or tools

Many failing tests were fixed. Four tests (partly related to zope.interface 5.1) are still open and in-progress. Jens would appreciate help to get them fixed and merged.


Timo Stollenwerk led the Volto efforts with Victor Fernandez de Alba, Rob Gietema, Steffen Ring, Katja Süss, Alok Kumar and Rodrigo Ferreira de Souza. They did a complete overhaul of the folder contents view according to Albert Casado's Pastanaga UI design, and made numerous other UI improvements based on a full UX review that Albert did. Alok (frontend) and Rodrigo (backend) implemented the Add-ons Control Panel and Alok implemented the Users and Groups Control Panel. Alok also implemented print CSS for the Volto front end. Victor fixed the listing block to remove the current item from query results for ZCatalog 5.1. Finally, Steffan and Katja worked on content for the upcoming website.

Image Scaling

Asko Soukka worked on image scaling in coordination with the Volto team, with additional help from Jens Klein and Alexander Loechel. They fixed several bugs:

They implemented an option (disabled by default) to generate all configured scales immediately once an image has been updated. Enabling this would slow down the save of an image field, but would prevent most writes on read for image scaling. The code is in plone.formwidget.namedfile.

They implemented a proof of concept for PLIP #3090 for asynchronous multiprocessing of image scaling, which compliments the above option to generate all configured scales on save. It could provide image scaling with good performance for Plone without any additional services.

They implemented a proof of concept for the use of picture & srcset in Volto for perfectly responsive images. The code is in Asko's Github account.

Mastering Plone 6

Philip Bauer led a team consisting of Steve Piercy, Katja Süss and Janina Hard to create and update the developer training class for Plone 6. Much was accomplished. The first alpha version of chapters 1 through 36 are now usable and will be deployed soon for testing.

Many of the chapters now exist in two flavors: one for Volto and one for Classic, with links between them. Logos at the top clearly identify which flavor you are reading. The default navigation follows the Volto story.

The team plans to do bi-weekly half day sprints and to finish the training at the Beethoven Sprint which is scheduled for May 26th. The outstanding chapters are: 

  • Customizing Volto
  • Membrane
  • Speaker content type and view component
  • Volto Frontpage

Plone Marketing

Sally Kleinfeldt and Érico Andrei investigated tools and planned a series of "how to" screencasts for the Plone Youtube channel about managing content in Plone. Érico also worked on adding the videos from the 2003 to 2009 Plone conferences to the channel.

Sally discussed how to position headless Plone and Volto with Timo Stollenwerk, Victor Fernandez de Alba and Katja Süss. As noted above, the Volto team is working on a new website which will primarily be aimed at React developer on-boarding. We discussed how can coordinate with and compliment their efforts.

After discussion with additional interested parties (Rikupekka Oksanen, Stefania Trabucchi, Fulvio Casali and William Fennie), we decided to create a "What is Plone?" section on which is aimed at decision makers. It will give a bit of Plone history and describe the current variety of frontend and backend options and when to use them. We began brainstorming ideas and will meet again in 3 weeks. Input from other community members would be welcome.