When specifying new Tiled Layers and Sprites in the Game Builder, the user must specify an image to use and the pixel height and width of tiles in the image. For the sake of multi-resolution portability (where different image resources would be used to accomodate different sizes) it would be better to specify the horizontal and vertical tile count instead.
The resulting generated code would calculate the tile width and height passed to the Sprite and TiledLayer classes using Image.getWidth and Image.getHeight as illustrated below (taken from GameBuilderDemo):
public TiledLayer getWater() throws java.io.IOException {                                 
if (Water == null) {                               
// write pre-init user code here
Image image = getTopview_tiles();
Water = new TiledLayer(8, 6, image, image.getWidth()/16, image.getHeight/7); 
...
}
return Water;
}