When using Surface 4 with external low-dpi monitor, a native dialog that is launched, is scaled properly on the Surface's main display (which is set to 200% scaling), but is scaled too much on the low dpi screen. This applies to at least File Dialog and Message Box.

Reproducible only on Surface, and only with per monitor scaling (dpiawareness=2). System aware scaling works fine (dpiawareness=1).

Attached screenshot shows the issue, File Dialog is taking most of the screen. Compare to the taskbar that is visible at bottom.

Steps to reproduce:

• Have main display (with high dpi) as primary display
• Run attached sample
• Click button "QFileDialog"
• Move the opened File Dialog to the low dpi secondary screen
• EXPECTED: File Dialog is proper, usable size
• ACTUAL: File Dialog is not scaled down to proper size compared to the high dpi screen, making it too big for the said screen to be usable