Heh heh! I have a hinged lid too! I got a panicky call from a cat sitter one summer when we were in Georgia... the tank was empty and the lid was ajar, and she feared going into the room to care for the cats.

Of course I had moved the snake somewhere more secure for exactly that reason... I knew the lid would be a problem.

I use a brick on EACH side of the hinge... makes for a cluttered top, since there is barely room for the light too!