i have a diffuse thin pattern but my hairline is somewhat thin i know rogaine isnt really for receding hairlines but would it make my hairline thicker?
Yes, Rogaine will help treat thinning of the hairline, and will help with hair growth in that area.
The manufacturer of Rogaine can only claim that the treatment will work on the vertex and may not on other areas because the clinical trials were done only on the crown. It will make hair grow at any place where applied topically onto the skin as long as hair follicles are present.
I myself apply Minoxidil, which is the generic name for Rogaine, in a Norwood 6 pattern all on the top of my scalp, since that's the way I'm thinning, and it works well.
For me it hasn't helped the hairline at all. Only grew some vellus hair and in a certain lighting it might seem that I have more hair but when I take a photo and compare it's very clear that the hairline has receded even further because those small hairs don't show in the photos. My crown/vertex is also slowly thinning but I haven't tried minoxidil there because it would stick to the hair and make it look even thinner.
A strange article I read today on balding blog was that finasteride reverses miniaturisation but minoxidil doesn't, although it grows new hair for some people.