Most Important Changes:
The most important change isn't immediately visible, namely a completely rewritten text layout engine, which supports complex scripts like Arabic, Hindi or Thai, as well as providing access to advanced OpenType features, such as ligatures and alternate glyphs.
Altogether, about 500 languages and/or scripts are supported. Please note that as of version 1.5.3, Scribus is supposed to render these diverse writing systems, which still needs thorough testing by those who are familiar with them.
Typing on the canvas and text rendering in general has become a lot faster.
Previews for fonts are now available in font selectors.
The "Text" tab has been removed from the Properties Palette and is now a separate UI palette.
The performance of copying and pasting objects in/from/to files with huge color palettes has been vastly improved.
An import filter for Krita's KRA format has been added.
Scribus now follows the XDG standard for configuration files. Therefore, the Scribus preferences directory has moved from ~/.scribus/ to a new default location: ~/.config/scribus/
Color selectors display the color values as a tooltip.
A longstanding problem with the launch option for an external image editing program has been resolved. Until version 1.5.3 it was necessary to manually close the external program before it could be started again from within Scribus. This is no longer necessary.
The "Wikipedia RAL Classic" color palette has been updated, this time using Wikipedia's LAB color values.
A script called "Caption" has been included, which adds a text frame to an image frame, based on the latter's proportions.
The "Autoquote" scripts now supports inverted guillemets via the "de-g" parameter.
As of version 1.5.3, the minimum Qt version to compile the program is 5.5.
Harfbuzz and libicu, as well as the related development packages are now required.
Some newly introduced features, like footnotes, may not function as desired, at least not yet.
The file format may undergo some changes between the current release and 1.6.0, so we advise caution when it comes to workflows that use automated document generation or parsing.
Vertical writing systems aren't supported for the time being, but support will be added in a later release.
The Online Help hasn't been completely updated, and it won't be until the final 1.6.0 release.