Title bar is being painted strangely

[davidc86]

This is kind of weird (and might be related to the blurry issue #1017, who knows?) but I'm seeing the Title Bar and top border on PTXprint splitting apart!

Yeah, weird. It also happens on the Preview Pane:

So, any time the PTXprint window gains focus, it repaints it like that.

But if it is not in focus, it looks normal:

Just an FYI. It is not a show-stopper.

NOTE: This only happens on my external 1080p monitor set at 100% scale. It doesn't happen on my laptop screen (3840 x 2160 at 200% scale). Weirdly, I can drag the PTXpint window back and forth across the two displays, and the title bar splits and rejoins each time I do it. So, highly repeatable. It happens as soon as the window rescales as it moves across to the external monitor. (Maybe I just need to go get me a high-end 3840 x 2160 external monitor, eh? Then no jumping the scaling back and forth.)

Here it is on my laptop screen: