I have this problem where I press the right click, and the mouse moves a few nanometer over the contextual-menu. When a release the right click, the system acts as if I just did a left click on the contextual-menu and do the action like "copy" or "change page"… This can lead to pretty annoying consequences.
The solution would be to stop the right click being treated as a left click when the mouse moves over the contextual-menu before the right click is released. I don't know if that's possible but honestly I doubt anybody use that feature in the first place.
Another solution would be to make the contextual menu appear after the right click is released, instead of after the right click is pressed, if that is possible.
Best Answer
You're clicking for too long.
If your mouse has a dodgy button, it may let go before you think you did, causing behaviour 2.
With behaviour 1, you can just take your time wandering around sub menus without having to click anything until you're completely ready. The menu will just wait for you.