Related #576 High/Low DPI Adapting

The Qt UI would change the size according to the logical DPI of the computer
Only Windows and Linux have been tested. (Should also work on Mac but have not tested).
The function is unfinished.
I was going to suggest overloading this function, but don't think that's possible in Python.

Instead you can try something like

```python
def adjust_dpi(width, height = None):
    if height is None:
        # QSize
    else:
        # width, height input
```

but it's not that much better.