The alert is not useful for users and only comes into play when using a widget
with the visible attribute set to false (this can be quite useful when wanting
to use javascript code generated by the widget).

So I propose removing the alert.

    else
    {
        //alert( "image object for " + this.szImageName + " not found?" );
    }

Another null check needs to be added for everything to work again since there
are now buttons in the application without images:

function CWCButton_SetState( nState )
{
    if (!this.oImage) return false;
    ...