I had reported this issue earlier, when I reported it last time I thought it was compiler bug. It isn't really a bug but I think it is better to report anyway.
To reproduce the problem: 1 Take any project which can work in both 0.7 and 0.8 build it with 0.7 2 Using 0.8(dev) to build and run it in js mode there will be js runtime error: TypeError: views.MyInitialView.superClass_.get__MXMLDescriptor is undefined [Learn More] MyInitialView.js:651:15 .MXMLDescriptor.get file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/views/MyInitialView.js:651:15 org.apache.flex.core.ContainerBase.prototype.addedToParent file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/org/apache/flex/core/ContainerBase.js:173:5 org.apache.flex.core.Application.prototype.addElement file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/org/apache/flex/core/Application.js:115:3 org.apache.flex.core.Application.prototype.initialize file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/org/apache/flex/core/Application.js:265:3 org.apache.flex.core.Application.prototype.start file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/org/apache/flex/core/Application.js:236:5 <anonymous> file:///Users/lipan/Downloads/testbmmljan09/bin/js-debug/index.html:188:3 The fix is simple, if you clean the project before build again it will work. My Apache Flex community contribution is working on the open source Moonshine-IDE.com for FlexJS.