window tint: 1. static cling; 2. MA laws

["G. Benedikt Rochow" <rochow@segsrv.hlo.dec.com>]

While the air is still cold, I'm getting summerly
temperatures in my 5kS, and I'm trying to avoid 
fixing the A/C by applying a bit of window tint.

1. I just spotted "static cling" (as opposed to 
glueing-by-moisture) window film at Wal-Mart.
Any positive/negative experiences with this?
(e.g. how well does it survive rolling doen a window?)

2. I seem to recall something about "max. 35% tint" on
the Massachusetts RMV web pages, as well as no
prohibitions on the front-side windows, but can't find 
it now. Does anybody know the laws here, and how 
they're enforced? 
I thought the rule was referring to % of light blocked, 
but the 2 levels of s-c film I saw said 20% light
passage and 35% passage, respectively.
 - so, is this 20% tint illegal?
 - is front-side (i.e. driver's door) window
   tinting illegal in MA?

I just took a look around the parking lot here, and many of
the few vehicles with tint had tint that looked darker than the
20% film in the store. On the other hand, none had the front doors'
windows tinted. 

???

TIA,
-gbr