Sometimes after playing for a random amount of time the mouse no longer acts as expected. When in advanced build mode the cursor disapears, the yellow box still moves, but the cursor is gone. After the mouse disapears, if a GUI is opened (ie the inventory or even the quit menu) the mouse is still not displayed and moving it actually moves the camera. The only way to get a GUI to work properly is to press F2 and detach the mouse. Once detached the mouse can only be used to press one GUI button, then any mouse action affects the universe again. ex quiting the game takes 2 mouse clicks one to click "quit game" and another to confirm, this action requires me to detach the mouse twice. This will only be resolved when the game is restarted.