Dock: Design Rule Checker
It is checked, if there are any other elements on the active layer then polygon with a circular shape. This function may be especially useful for layers which are drilled.
Additionally the circles can also be check in its radius. A check for a minimum radius als well as a maximum radius is possible. The radius check was introduced with version 20150128.
For general setup like check region and error layer please see the DesignRuleChecker documentation.