Mega Menu
Not sure if this is a bug, but I replicated the issue on a blanco page with the nav item from the library inserted.
When resizing the window the modal appears for a brief moment.
Link to recording
Do I mis something or oversee something?
Environment info
I think it’s by design.
You can add something basic like this to your nav block:
.blockclass:not(.cc-nav--open) .cc-nav-wrapper {
transition-duration: 0s;
}
or as a general rule:
.cc-nav:not(.cc-nav--open) .cc-nav-wrapper {
transition-duration: 0s;
}
Didn’t test extensively, use at your own risk.
Maybe this behaviour can be improved in the future, but not sure if it’s needed.
Thank you Marius 
Maybe it’s a personal preference, I personally don’t like the ‘glitch’. It’s like there is something wrong with the site.
You definitely have a point here.
Just didn’t want to directly agree, since I didn’t check the circumstances in detail yet.
I think for the regular visitor this shouldn’t be a thing.
But I can see some potential trouble when clients are checking their sites 
Maybe it are my “compulsive-neurotic-design-habits” 
And, exactly what you are saying, I’m looking also through the eyes of clients.
Again thanks Marius 