I noticed that if I set to “true” the “enabled” attribute of the <Warning_NoTypeDecl> tag in “/en/Configuration/Actionscript 3.0/EnabledWarnings.xml” I get warnings from classes located inside these files: StyleManager.as, UIComponent.as, LabelButton.as, Button.as and so on 
Warning like these:
Warning: 1008: return value for function ‘getInstance’ has no type declaration.
Warning: 1008: return value for function ‘setIMEMode’ has no type declaration.