I'm just getting my feet wet with plugin development so please excuse me for silly questions :)
I have a really simple LocalInspectionTool that checks for invalid xml attributes. I do something like this:
public void visitXmlAttribute(XmlAttribute attribute)
When I create a html file and add a foo=bar attribute to a tag it is correctly marked with "invalid.attribute.test". Cool. But it is marked 5 times :) I don't understand where the duplicate warnings come from.