MCreator is Copying own pages and confuses me

This is a render problem from what I can see, it might be a out of data driver, this happens to me on my second monitor, over HDMI does not like it but its fine on vga so its down to how the computer and app are rendering.

@#1.1 I say give that a try yes its always a good idea to make sure your rig is up to date and JAVA is up to date so you can rule out them been at fault :)

The cog has a GUI setting maybe try click that see if that changes its raction to your PC, I am not sure what else to say on my laptop I never get the glich only on my PC when I put it on to the HDMI screen and I am out and about at the moment so can't test other ideas, maybe change compatibly mods, mess with the screen settings just to see what affects it.

I feel it's a draw problem but finding out if its the app or the OS creating the problem is 
another story, I get it when its on my HDMI screen and when a window opens up on my other screen it does it, do you have multi screens? 

Try change the second monitor as your prim and try it on that, it could be down to way its rendering two screens, like I said its something I found in my work.

You only need to make it the main how you test, you need to do all these kinds of checks to see what's happing :P  but also ya try drag it over also, test everything you can thing of.