I guess you can define MouseListener
var oMouseListener:Object = new Object();
And each time there is a Mouse click
oMouseListener.onMouseDown = function() {
// reset you TF focus here
}
Mouse.addListener(oMouseListener);
inside your onMouseDown method, you can reset the focus for the textfield you like. As soon as you dont need the listener (because its triggered each time user presses a mouse button), use
Mouse.removeListener(oMouseListener);
to remove the listener…
Well, depends on what you want to achieve… don’t know perhaps there is more direct way to achieve the same… or better 
Hope it helped 
