I just installed Windows 8.1 on my laptop and tried out the new scaling for the desktop when using multiple monitors with different DPIs.
It is improved and more usable now, but still has issues unfortunately.
I've played with it for a few minutes and this is what I've learned
- UI elements will now be the right physical size on any screen regardless of the DPI
- UI elements are still actually rendered at one scale factor, the scale factor of the primary display
- UI is stretched or shrunk to be the right size on any display not using the current scale factor
- Scale factor still requires log out and log in to change
The common scenario that people will be having this problem with is using all the new high DPI laptops and tablets with external standard DPI monitors.
In Windows 8 if you set scaling to 125% or 150% to be the right physical size on the laptop everything will be way too big on the external screen when plugged in.
Now everything will be the right physical size but this is done by stretching or shrinking the pixels, causing re-sizing distortion and loss of crispness. But you will at least be able to use screens with different DPIs without one being too large or too small.
So lets say you're using your ATIV Smart PC Pro, Surface Pro, or other high DPI device undocked with 150% scaling on the screen. This works all great. Now plug in your external monitor.
- On Windows 8 everything is HUGE
- On Windows 8.1 everything is the right physical size but now blurry because they were shrunk down to 2/3 their previous size, a non-integer amount causing blurriness
Now lets say you'll be using the external monitor for some time and want the graphics to be optimized for it
- On Windows 8 you had to go to the scaling options, change to 100%, log out, and log back in. This causes the external monitor to operate optimally but now everything is tiny on the built-in screen. Tough luck.
- On Windows 8.1 you just need to log out and back in. No need to change any settings. The external monitor is now operating optimally. The internal screen on the device still shows everything the correct size, but is now stretching everything 150%, causing them to be blurry.
There are a few exceptions.
- IE11 will always render at the current scale factor, no matter which monitor it is on. You can zoom the pages in and out.
- Taskbar always renders at current scale factor
- Task manager will always render at current scale factor
Time to unplug external monitor and go mobile.
- On Windows 8 you had to go into the scaling options, set to 150%, log out, log in. If you do not do this, everything will continue to render at 100% and be too small.
- On Windows 8.1 you just have to log out and back in. If you do not do this, everything will render at the right physical size but be stretched by 150% causing them to be blurry.
Metro works perfectly and did in Windows 8.0
Note: This was tested using a laptop with standard DPI, an external screen with standard DPI set to 125%. I no longer have a high DPI ATIV Smart PC Pro but was still interested in this. If anyone finds anything wrong please reply.