That is true for the FM2, FM2n, FE2, FA, and FM3a. Not true for the FM and the FE.
A link showing a pic of an FM body with the button plainly in sight is here: http://www.flickr.com/photos/marcus20/3618725672/
APUG: F4, F3P, F2ASx2, F, FM2n, Nikomat FTn - all blk bodies; Nikomat FT2 chrome
Nikkors: 18-70/3.5-4.5G AF-S DX (for DPUG), 28/3.5 H, 35/2 O, 50/2 H x2, 50/1.4 S, 55/2.8 Micro AIS, 85/1.8 K, 200/4 AI, 300/4.5 EDIF AIS
My FB - My flickr stream