Not ideal, but you can manually change the properties of the project.
I did this with a Flex Project called Test. Fill in the steps with your own project.
- Close Flex Builder
- Navigate to the directory containing the Test Project's files (bin-debug, html template, etc.)
- In this directory there is a hidden file called .actionScriptProperties. Make the following changes:
I marked the changes with <!-- old (the new tags are just below these old tags)
<?xml version="1.0" encoding="UTF-8"?>
<!-- old <actionScriptProperties mainApplicationPath="Test.mxml" version="3"> -->
<actionScriptProperties mainApplicationPath="NewTest.as" version="3">
<compiler additionalCompilerArguments="-locale en_US" copyDependentFiles="true" enableModuleDebug="true" generateAccessible="false" htmlExpressInstall="true" htmlGenerate="true" htmlHistoryManagement="true" htmlPlayerVersion="9.0.124" htmlPlayerVersionCheck="true" outputFolderPath="bin-debug" sourceFolderPath="src" strict="true" useApolloConfig="false" verifyDigests="true" warn="true">
<compilerSourcePath/>
<libraryPath defaultLinkType="1">
<libraryPathEntry kind="4" path=""/>
<libraryPathEntry kind="1" linkType="1" path="libs"/>
</libraryPath>
<sourceAttachmentPath/>
</compiler>
<applications>
<!-- old <application path="Test.mxml"/> -->
<application path="NewTest.as"/>
</applications>
<modules/>
<buildCSSFiles/>
</actionScriptProperties>
Not sure if that helps. Good luck man!