After a long time, and no sound about kgeogeo and his very useful addon, i made some improvement for Blender 2.78+
Now you can use it with mask stencil too!
Here a nice video by my friend Craig Jones: LINK
Here is my github for “Stencil Widget” add-on:
Wow, it’s great!
Thank you for sharing this addon.
Spirou4D,
Totemo yakudatu addon wo arigatou! （とても役立つアドオンをありがとう！）
= Thanks you for the very useful addon!
Onegaishimasu. すべての喜びは私のものです。
Good blend.
Good tool. Thanks
niceeeeeeeeeeeeee
Thanks a lot for this.
Looks like zbrush spot light texture. Will test it…thx for sharing
Yes mkbreuer
like Zbrush.
Very useful for painting, the interactive tool is amazing.
“Trying is adopting!” LOL
Any news if this has been port to 2.8?
Sorry, but not ported to b2.8 yet… I planed this year to work for this.
I am sick now…And i have made a lot of change with my computer. All that is now ended and I project to code first this add-on after a lot of change of blender 2.8 2.81 2.82.
At soon …
Thanks for notice.
Wish you all the best, so get well first, then everything else will fit to place 
Thank for the reply and i hope you get well soon!
@ polynut & burnin
Thks for your friendly wishes, you make me happy for this day.
At soon for best news…
Hi Spirou !
Tho it’s not what i’m ( struggling ) searching for, for years, your ( it appears not to be an addon as i cannot find it in prefs->addons after coying in in addons folder ) code seems very interresting for easing painting on meshes 
thanks for this and…
happy blending !
I wish you a… ‘prompt rétablissement’ !
Hoping to hear from you very soon !
Does it work with blender 2.91(2.92)? And if not, are there any plans to update it? May be you know of any devs’ plans to make stencils more convenient?
No for b2.8+
I have not enough energy to continue…because blender api is changed with openGL and I don’t know details with it…
Probably the best action is to present this to Pablo when he starts to work on Texture Paint after his work with Sculpt slows down - because it will benefit all paint modes, it should be a default UI feature. Spirou4D has worked so long on this, but like he says, the code base changed enough to make it foreign and confusing and not a simple fix.
