I have an alarm i need to disarm!!!!!?

Okay so in my bed room window; i have a Brinks Home security alarm. so when my window opens and the alarm is on; the alarm will set off, well there is a magnetic part glued to my window and a magnetic part that is screwed to the window sill at the top. The magnetic squares are the things that when they pass eachother; the alarm will set off. is there anyway to deflect it? like put something over the magnetic part that in on the actual window so the alarm wont detect that the window is open?