Focus Flex App on start up

When a flex application loads it doesn't actually have focus until the user clicks on it.

So even though you can call setFocus() on a TextInput or Button and visually it appears that your control has focus (blue border), if you try to type you'll notice that nothing happens. This can be quite frustrating for a user.

One way to solve this is to edit the html file that loads your application (e.g. the index.template.html), and call the JavaScript focus() function on the flash element. I found this website explains it quite nicely:
http://www.appfoundation.com/blogs/giametta/2007/07/09/internet-explorer-setting-focus-on-flex-apps-flash-player/.

If for prefer to keep all your code in ActionScript you can accomplish the same thing by doing this:

 ExternalInterface.call("function() { var app = document.getElementById('"+id+"'); app.tabIndex = 0; app.focus(); }");

I usually put that line of code inside my applicationComplete event handler.

One other thing to note is that if you call setFocus on a component that isn't finished being initialized it won't always work. For best results call setFocus() in a creationComplete event handler.

I added the app.tabIndex = 0 after finding that the focus didn't work on Safari. This came from stackoverflow.