Theme Designer Mode
From MoodleDocs
Settings > Site Administration > Appearance > Themes > Theme settings
Enabling this setting in Moodle 2.0+ themes stops Moodle caching the data of the elements you are working on.
Note: You are currently viewing documentation for Moodle 3.4. Up-to-date documentation for the latest stable version of Moodle is likely available here: Theme Designer Mode.
Enabling this setting in Moodle 2.0+ themes stops Moodle caching the data of the elements you are working on.