@crackwitz Please pay attention on CI. The PR breaks build.

how should I handle this? all the existing code for every function is structured such that there is an extern C implementation of the respective function per toolkit, and then one namespaced wrapper function calling that.

I could remove the CV_IMPL (extern C) from all implementations of cvPollKey so it iself is not exposed. I think that will then require a forward declaration in window.cpp before/inside of cv::pollKey since the C function isn't declared in a common header anymore.

edit: that is... if CVAPI(int) cvPollKey(void); in highgui_c.h needs to go, I'll need to provide that declaration in some other way. maybe I misunderstand.

ok, looks like I did it right this time. I hope the structure is as desired.

@crackwitz Please squash commits to have clean changes history in OpenCV git.

here are the requested changes. I hope I understood the intention.

I'll squash when you're satisfied with the state of the pull request and any discussion has resolved. squashing implies force-push; I hope that's correct.

This function's purpose is updating UI too (like waitKey())

I understand that. I'm not sure if waitKey should be given a more suitable name as well.

I've squashed the commits so far and rebased to current master HEAD.