Here’s a funny quirk. If you create a project in Flex Builder and call it Test for example, it will automatically use that as the name for the main MXML application file Test.mxml (case included). If however you give your project name a hyphen, like Test-Name. it won’t use it at all and will instead use the name main.mxml.
The same happens if you have spaces in your project name. Now obviously if you named your project using a lowercase name this isn’t an issue. However, from memory all of the examples and I am sure a “best practice” document somewhere states that projects names (and the subsequent default application MXML file should be capitalized.
Considering you can uses these conventions in the project name, one would expect the creation of the main MXML name to at least follow the same case convention in auto naming that is used when hyphens and spaces are omitted or the alternate file it creates. i.e. Main.mxml if the project is capitalized not main.mxml as it currently is.
Personally I think that this should be a enhancement request to fix this inconsistency…