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 188.8.131.5276, and currently 184.108.40.20601.
Is there a compiler argument that can resolve this?