GolfproMike: game play is still in window on all sizes.
If you try F11, it will send your browser into 'full screen' mode.
If you have a widescreen monitor, there is no way I know of to eliminate the black bars to the left and right. This doesnt mean you are NOT in full screen. It just means the game itself is formatted to suit all monitors, including the old 'square' type CRTs
This is called Aspect Ratio and WGT has it in 4:3 whereas your widescreen monitor will be 16:9 (or perhaps 16:10)
Changing Resolution wont alter your Aspect Ratio.
Perhaps trying different resolutions unto you find one you are happy with, but you may find the images are skewed horizontal or vertical.