@leocg I have done all of those steps. and this problem has been there for over 1 year across many windows versions and many opera versions. I have even uploaded a video...don't know what else i could do.

no reply in 2 days? looks like time to uninstall

weird bar appears and disappears at the bottom everytime i minimize and maximize. It resizes the content on screen. This has been happening since a year and happens on many websites like fb,youtube etc.
I have recorded a video: https://www.youtube.com/watch?v=duzIxLPrcd4&feature=youtu.be
Plz check. Its annoying.