Basically, I'd like to have a project where I don't need to define any MXML or that doesn't need to include the Flex component libraries. I simply choose the main class (extending a Sprite) that I have implemented in AS, and that class will be added on the stage as a the root object. Please try the following in FlexBuilder (you hopefully have at least one license for it and if you don't, there is a 60 day evaluation license available): 1) Go to File / New / ActionScript Project 2) Enter "Test" as project name and click "Finish" 3) The project with "Test.as" will be created. Implement some code, e.g: public function Test() { var textField : TextField = new TextField(); textField.text = "Hello World!"; addChild(textField); } 4) Go to Run / Run Test You should see "Hello World!" on the screen. No MXML or Flex components involved.