Pre SCSS callback makes it hard to extend Boost

Test 1 Use Boost Chang the accent colour and confirm that it took effect Look at the generated CSS and confirm that... ... the box-sizing properties are also prefixed webkit ... RTL styles are automatically flipped Confirm that uploading a custom preset works as well Sample SCSS file:   // Body $body-bg: #ff9900 !default; $body-color: #fff !default;   // Import everything. @import "moodle"; Test 2 Install the attached theme (extendsboost) Make sure that the theme's config.php comments out scss and csstreepostprocessor . Confirm that the theme looks like Boost only the accent colour and preset settings from Boost do not have any effect Look at the generated CSS and confirm that... ... the box-sizing properties are also prefixed ' webkit ' ... RTL styles are automatically flipped Enable the csstreepostprocessor property in the theme's config.php Confirm that ... the a CSS rule setting the body background color to red was appended to the CSS box-sizing is no longer prefixed styles are flipped in RTL Now enable the theme's scss property Confirm that the only CSS defined is setting the body background to green.