This changed the result as follows but as Hello World has no event listeners I'm not sure what the new errors mean.
Information:[MySite]: Starting Flex compiler: "C:\Program Files\JetBrains\IntelliJ IDEA 2017.2.3\jre64\bin\java.exe" -Dapplication.home=C:\FlexJSSDKs\0.9.0 -Dfile.encoding=UTF-8 -Djava.awt.headless=true -Duser.language=en -Duser.region=en -Xmx512m -classpath "C:\Program Files\JetBrains\IntelliJ IDEA 2017.2.3\plugins\flex\lib\idea-flex-compiler-fix.jar;C:\Program Files\JetBrains\IntelliJ IDEA 2017.2.3\plugins\flex\lib\flex-compiler.jar;C:\FlexJSSDKs\0.9.0\lib\flex-compiler-oem.jar" com.intellij.flex.compiler.FlexCompiler 62471 Information:[MySite]: mxmlc -load-config=C:\Users\Doug\.IntelliJIdea2017.2\system\compile-server\tabletbookingwebsite_b0893d28\_temp_\IntelliJ_IDEA\idea-2B980A45-2D8F3090.xml -load-config+=C:/FlexJSSDKs/0.9.0/ide/IDEA/intellij-config.xml -targets=JSFlex -external-library-path+=C:/FlexJSSDKs/0.9.0/js/libs/js.swc -allow-subclass-overrides=true Information:[MySite]: Compilation failed Information:07/09/2017 16:22 - Compilation completed with 4 errors and 0 warnings in 5s 562ms Error:[MySite]: : interface method addEventListener in interface IEventDispatcher is implemented with an incompatible signature in class MySite Error:[MySite]: : interface method removeEventListener in interface IEventDispatcher is implemented with an incompatible signature in class MySite C:\My Documents\FlexJS Projects\MySite\src\MySite.mxml Error:[MySite]: interface method element in interface IInitialViewApplication not implemented by class MySite Error:[MySite]: interface method element in interface IRenderedObject not implemented by class MySite -- Sent from: http://apache-flex-users.2333346.n4.nabble.com/