What do you mean?

@WereCat One example being when you drag e.g.. a Google Chrome tab/window from the 4k-monitor to the 1080p-monitor because it resizes itself in a odd way.

Another example is sizing. I sometimes use VLC to play some videos and the interface again, resizes itself in a odd kind of way.

Also this is my first time having a setup using a 4k-monitor and 2x-1080p-monitors together

Just imagine the setup I had for a short time. I found my old 1280x1024 Samsung monitor and just hooked it up next to my 4k Screen......weird. just weird. 

@mapegl Haha lol

I have a 1280-1024 next to a 1440p. Fun stuff.

I have 1440p and 1080p but I am using custom 1440p res for the 1080p display to get the extra screen real estate. Some apps look blurry (Steam, SpeedFan, etc...) but otherwise, it is a lot better.

Nice! I'm using this monitor instead of a 1440-900 because it adjusts roughly to the same physical size at my 1440p, so I can line up the bottom.

Could Windows be scaling the window(s) to the other screens, based upon native Resolution? (like the number of pixels gets preserved, even if the pixel density of one screen is higher than the other) Rather than physical dimensions?