I found the code in SkinnableTextBase.as
, under focusInHandler()
:
...
// the flag's old value.
var oldShowFocusIndicator:Boolean;
// Only editable text should have a focus ring.
if (enabled && editable && focusManager)
{
oldShowFocusIndicator = focusManager.showFocusIndicator;
focusManager.showFocusIndicator = true;
...
I needed to subclass TextInput (which is a subclass of SkinnableTextBase), and replace this with if (enabled && focusManager)
.