Well, I don't use Windows very much and I don't use GIMP for Windows but my understanding is that GIMP 2.8.12/14 for Windows was initially released with Windows libraries (dll's) that were not fully compatible. So, Windows users were having to roll back to the older, more compatible Windows' libraries used in GIMP 2.8.10. I don't know all of the issues caused by the packaging of incompatible Windows' .dll's, but there were several.
Onkel Hatti outlined the offending dll's in
this postQuote:
Jernej Simoncic used the newest libraries, that were available, when building the windows installer. It is not gimps fault, it is the fault of the 3rd party libraries, so I think, Jernej Simoncic will create a new installer soon. In the meanttime, exchange
libgtk-win32-2.0.0.dll
libcairo-2.dll
libpixman-1-0.dll
with the versions from gimp-2.8.10
I wouldn't consider issues caused by the incompatible Windows libraries to be GIMP "bugs" because GIMP 2.8.12/14 works fine in Linux. It was more of a Windows packaging and installation problem.
GIMP 2.8.15 from Samj appears to be a new compile from the daily Windows compiles, with the stroke bug fixed. It's also been packaged to be portable and includes the more compatible libraries, as well as the addition of several popular plug-ins.