back button behavior in android in appcelerator alloy application

I am having trouble understanding the back button behavior in my alloy application in android. The scenario is this:

I am loading a widget in one of my windows to which I pass some parameters to use. I am retrieving these arguments in the standard way:

var args = arguments[0] || {};

On window close, I am setting the args to null. Now, this works fine as long as I close the window using my close button. args is set to null, and re-instantiated when I open the window again.

When I close the window with back button, args is set to null, but is never re-instantiated once I open the window again, and remains null. I have checked this with both heavyweight and light windows.

What all things does back button do? How can I enable re-instantiation of all the arguments again on opening the window?

Code: index.xml

<Alloy>
    <Window id="myWin" class="container">
        <View layout="vertical">
            <Require type="widget" src="myWidget" id="myWidget" title='mainWindow' close='mainWindow' />
        </View>
    </Window>
</Alloy>

index.js:

// setting args to null on window close
$.myWin.addEventListener('close', function () {
    $.myWidget.resetData();
});

Inside myWidget's controller, widget.js:

var args = arguments[0] || {};

// sets args to null
function resetData() {
    args = null;
}

exports.resetData = resetData;

The above code does not re-initiate args once set to null (when we close window with back button). If however, I export args and set it to null in window controller, it shows there that args is null, but args has all the data once we re-open the window again even though it is not initiated again.

Code: index.js

$.myWin.addEventListener('close', function () {
    $.myWidget.args = null;
});

Inside myWidget's controller, widget.js:

exports.args = args;

What exactly is going on here?