AS3: setSelection Up Arrow Override - actionscript-3

Question

I would like to focus on the end of a TextField when the up arrow is pressed. I'm using:
txt.setSelection(txt.text.length,txt.text.length);
This works great for any key except the up arrow. I believe that the up arrow automatically sets selection to the beginning of a TextField when it is in focus. How can I override this default behaviour?

Answer 1

I wanted to change the behavior of the home key, this is how I did it :
(The following code should essentially disable the HOME key but can be modified to make it do anything)
// Create two variables two remember the TextField's selection
// so that it can be restored later. These varaibles correspong
// to TextField.selectionBeginIndex and TextField.selectionEndIndex
var overrideSelectionBeginIndex:int = -1;
var overrideSelectionEndIndex:int;
// Create a KEY_DOWN listener to intercept the event ->
// (Assuming that you have a TextField named 'input')
input.addEventListener(KeyboardEvent.KEY_DOWN, event_inputKeyDown, false, 0, true);
function event_inputKeyDown(event:KeyboardEvent):void{
if(event.keyCode == Keyboard.HOME){
if(overrideSelectionBeginIndex == -1){
stage.addEventListener(Event.RENDER, event_inputOverrideKeyDown, false, 0, true);
stage.invalidate();
}
// At this point the variables 'overrideSelectionBeginIndex'
// and 'overrideSelectionEndIndex' could be set to whatever
// you want but for this example they just store the
// input's selection before the home key changes it.
overrideSelectionBeginIndex = input.selectionBeginIndex;
overrideSelectionEndIndex = input.selectionEndIndex;
}
}
// Create a function that will be called after the key is
// pressed to override it's behavior
function event_inputOverrideKeyDown(event:Event):void{
// Restore the selection
input.setSelection(overrideSelectionBeginIndex, overrideSelectionEndIndex);
// Clean up
stage.removeEventListener(Event.RENDER, event_inputOverrideKeyDown);
overrideSelectionBeginIndex = -1;
overrideSelectionEndIndex = -1;
}

Answer 2

there is the Prevent Default (livedocs) function you can apply to the action if it is cancelable (which i presume it would be) otherwise you can try and catch it with stopPropagation instead:
This hasnt been tested, but should look something like:
function buttonPress(ev:KeyboardEvent):void{
txt.setSelection(txt.text.length,txt.text.length);
ev.preventDefault();
}