Dock: Design Rule Checker
It is checked, whether two layers have a distance less than a entered value. The value and the two layers are entered in a dialog. The location of the lowest distance will be marked.
Alternative it can be checked, if any shape on layer1 has a shape on layer2 next to it which not more than the given distance away. The other way round is not checks. (layer2 has a layer1 next to it) This option was introduced with version 20130618.
For general setup like check region and error layer please see the DesignRuleChecker documentation.