Oxygen XML Editor includes a built-in LESS CSS Validator, integrated with general validation support. The usual validation features for presenting errors also available for LESS stylesheets.
Oxygen XML Editor provides three validation methods:
- Automatic validation as you type - marks validation errors in the document as you are editing.
- Validation upon request, by pressing the
Validate button from the 
Validation toolbar
drop-down menu. An error list is presented in the message panel at the bottom of the
editor. - Validation scenarios, by selecting
Configure Validation
Scenario(s) from the Validation toolbar drop-down menu. Errors are
presented in the message panel at the bottom of the editor. This is useful when you need
to validate the current file as part of a larger LESS import hierarchy (for instance, you
may change the URL of the file to validate to the root of the hierarchy).