It would be nice to be able to construct a new hud widget, pass the actual texture rather than string, and the alpha flag. And also be able to set the alpha flag after it is constructor.
This is already possible. A Texture is always passable as a string (name) and the boolean alpha flag or as Texture instance. A Texture is always loaded by TextureLoader with or without alpha channel. The alpha information is stored inside the Texture.
So you could either load a Texture by
Texture tex = TextureLoader.getInstance().getTexture( "bla.png", Texture.RGBA );
Image img = new Image( 640f, 480f, tex ); // this is a HUD Image Widget (not an AWT Image)
or by
Image img = new Image( 640f, 480f, "bla.png", true ); // this is a HUD Image Widget (not an AWT Image)
which will produce the exact same result.
Or course the amount of transparency is defined by the Texture itself. Using a user-defined alpha value is is also imaginable, but not (yet) possible.
Marvin