Windows support for HiDPI displays, call for feedback and testing

[Dr. Michael Paus]

I cannot provide any Windows specific feedback on HiDPI displays because
I don't own one but I am working on a MacBook Pro with Retina display 
and thus would like to ask a few questions in this context.

How are other platforms (Mac, Linux) affected by the changes you made 
for the Windows support? (On my Mac I noticed a severe performance drop 
when using 8u60 which may possibly be related to these changes.)

Are any of the special system properties you mentioned also usable on 
other platforms?

Is there any way now to find out what the current pixel scale factor is?
Without that knowledge it is impossible to do proper graphics on any 
HiDPI screen. (E.g., you can't position graphic elements correctly in 
order to get crisp lines or you can't get a crisp snapshot of a node if 
you don't take special actions based on the pixel scale.)