Corrected issue with mouse position being at top left of crosshair image by offsetting mouse event X and Y coordinates by half the width and height of the cursor image. Also corrected NullPointerException that occurred when the player collected an ammo crate with ammo for a weapon he did not have. This normally should not happen, but I noticed that if I clicked fast enough past the death and title screens, that when I started over, all the weapons and ammo crates from the previous game would still be there.