New features in 2.3.0.beta3
Rebuild required. The rebuild will pick up on important NGINX changes required for letter avatar caching, and must be completed if the site has not be been rebuilt from the command line in the last 2 weeks.
Theme improvements
Discourse now supports editing settings and translations via the editor on theme-creator.discourse.org. When creating/editing a theme, users can access the settings and translations tabs right from the editor, no need to edit the theme locally.
Theme creator also now supports editing all theme metadata information, including license URLs, authors, and supported Discourse versions. Specifying supported versions allows theme creators to prevent themes from being used on Discourse versions which are missing support for theme features due to being too old, or from running on newer versions which may have breaking changes. If the Discourse version is outside the support versions for a theme, the theme will automatically be disabled.
Smooth J/K navigation when using keyboard
Discourse supports many keyboard shortcuts. Type ? when browsing Discourse to see them. For those that like to read Discourse with just the keyboard, navigating between posts via j/k is indispensable. However, this navigation didn’t work well with long posts, as it would jump to the next (or previous) post, even if the entire post didn’t fit onto your screen.
Now, j/k will scroll within long posts, so you can read the entire post before jumping to the next one. For complete details and to provide feedback, see Smooth J/K navigation when using keyboard.
Improved image resizing discoverability
When large images are uploaded, Discourse automatically scales them to fit within the post stream. Users can click on the image to view the image full size, and to download it.
Sometimes, users do not want images to take up the full-width of the post stream, so Discourse supports resizing images. To do so users must add ,xx% to the image dimensions. To make this more discoverable, users can now resize images to common percentages (100, 75, & 50%) by hovering over the image preview and selecting the size they want. To make more specific adjustments, users can then edit the raw image markup.
Example:
Via markup, you can also use pixels to resize to a specific width or height.
Example (width at 200px, auto-height):
Example (height at 200px, auto-width, useful especially for multiple same-height images side-by-side):
 
Merge share and invite actions together
Want to share a topic or invite a user? The share and invite actions have been merged to a single modal. Select the “
Share” button from the topic footer to access the share/invite modal. This change also adds support for inviting users on mobile, as topic invites were previously a desktop-only feature.
iPad composer improvements
Unfortunately Apple does not provide support for JavaScript to detect if a hardware keyboard is attached, or if a software keyboard is visible. For this reason, Discourse has to assume there’s a software keyboard visible. For more details, see iPad with external keyboard connected can't see post when replying, and check out the bug report filed with Apple: 176205 – On webkit ios there is now way for accounting for virtual keyboard height.
However, we’ve continued to make changes to improve Discourse usage on an iPad, despite the limitations. In this beta we added a new user preference which allows users to specify that a physical keyboard is connected. We also added support for using Alt + Enter to submit a post, and for focus to be set in the composer textarea.