No error is thrown by the SWF after making a change to the class containing this code and then compiling. However, if I compile again with no change to the class in question, the "Error #1065: Variable ClassName_CloseButtonImage is not defined" error is thrown.
This behavior only started after switching mxmlc compilers. Previously SDK 22.214.171.12476, and currently 126.96.36.19901.
Is there a compiler argument that can resolve this?