From GB's walkthrough:
A right click opens your inventory at the bottom of the screen. Place the bag over one of the inventory slots, and click again to place it here. Another right click closes the inventory bar. Note the other buttons on the inventory bar: the one on the bottom left returns you to the main game page (to save, load, quit, etc.); the eye above it gives a close-up of selected inventory items (you must grasp them first); the map to the right brings up a large scale map of the area;, and the bottom right symbol allows access to the encyclopedia pages.
Does that help, or does the game still seem different?