Cursor shown through object

I want a cursor to appear when a certain object is in view at the location of the cursor on screen. So for instance i have a cursor set up in the center of the screen but it doesnt appear unless looking through a specific window. So if i were to walk by said window if i was looking through it it would appear. Another way i can deacribe what i need help with would be

The visible unity camera layer is layer1 and a certain transparent window when looked through will display things on camera layer 2. Much like masking i suppose in the sense that i understand it as where the certain cursor is only visible when the transparent window comes across the location on screen where said cursor is and is looked through. Any ideas?