Resources

Keyboard navigation

Keyboard navigation support in the theme accessibility-ready guidelines
Keyboard navigation testing in the Accessibility Team’s documentation site
Keyboard accessibility by WebAIM

Reviewing

A Guide to Reviewing Themes for the WordPress Theme Repository by Chip Bennett
Preliminary Theme Review Process by Emil Uzelac
Prefix all the things by Justin Tadlock
Most Common Admin Review Issues by Emil Uzelac

Theme Options/Data Security

Using Sane Defaults in Themes by Chip Bennett
Custom CSS boxes in themes by Justin Tadlock
A Guide to Writing Secure Themes – Part 1: Introduction by Fränk Klein
A Guide to Writing Secure Themes – Part 2: Validation by Fränk Klein
A Guide to Writing Secure Themes – Part 3: Sanitization by Fränk Klein
A Guide to Writing Secure Themes – Part 4: Securing Post Meta by Fränk Klein
When And How To Escape Core Functions In WPORG Themes by Milana Cap
List of functions that are escaped, from the WordPress Coding standards.

Customizer

Customizer tutorials and documentation by Justin Tadlock
Moving to the Customizer API from the Settings API, using Options API by Chip Bennett

Review Videos

October 2016: Talking about escaping, validation and a few other things.
November 2016: Translation for themes and repo guidelines.
December 2016: Enqueuing scripts and stylesheets within WordPress and better practices for themes.
January 2017: Tools for reviewing themes: Local environments and testing tools.
February 2017: Hooks (Actions and Filters)

Licenses – Bundled Resources

GPL-Compatible Image Licenses

These licenses are GPL compatible and suitable for images:

CC0
CC BY 4.0
CC-BY-SA 4.0 – Compatible with the GPLv3 only.

If the license is not listed here, then it’s not compatible: https://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses

Recommended websites (for images):

wordpress.org/photos
Pexels
Only CCO License, not the pexels licence.
- To find the license, click on the small link that says free to use. If the headline says “Legal Simplicity.” then the image uses the Pexels license. The limitations are listed in the second section.
stocksnap.io
skitterphoto.com
mystock.photos
pickupimage .com
pxhere.com
foodiesfeed.com
Smithsonian Open Access

Restricted websites:

The license agreement or terms on these websites are not compatible with GPL:

unsplash.com
freeimages.com
scx.hu
photopin.com
splitshire.com
pixabay.com
freepik.com
flaticon.com
pikwizard.com
adobe stock
envato elements
undraw.co

GPL-Compatible Font Licenses

The GNU Foundation and the Fedora Project maintain lists of acceptable licenses for use with GPL.

Fonts bundled with Themes submitted to the WordPress Theme directory are required to be licensed under one of the following font licenses:

Arphic Public License (Arphic)
Baekmuk License (Baekmuk)
Bitstream Vera License (Bitstream Vera)
GNU GPL (with font exception) (GPL)
GUST e-Foundry Font License/LaTeX Project Public License (LPPL)
IPA Font License (IPA)
Liberation Font License (Liberation)
LaTeX Project Public License (LPPL)
mplus Font License (mplus)
ParaType Font License (PTFL)
SIL Open Font License (OFL)
STIX Fonts User License (STIX)
Ubuntu Font License (UFL)
Wadalab Fonts License (Wadalab)
XANO Mincho Font License (XANO)

GPL-Compatible Icon Sets

Some compatible icon sets include the following:

Genericons (GPL)
GNOME Desktop Icons (GPL)
Elegant Media Icons (GPL)
Humility Icons (GPL)
Flat For Linux (GPL)
Ultimate GNOME Icons (GPL)
Shrunk Pidgin Smilies (GPL)
Twotiny Icons (GPL)
Web Design Creatives (GPL)
realistiK Reloaded (GPL)
Carpelinx (GPL)
DarkGlass Reworked (GPL)
Lynx Black (GPL)
KDE Crystal Diamond (GPL)
Lifetime Social Networks (GPL)
Social Media Icons from Elegant Themes (GPL)
Font Awesome 3.0 (SIL Open-Font License)
Entypo (SIL Open-Font License)
Ligature Symbols (SIL Open-Font License)
SocioCons (GPL)