Zooming level is broken if XFCE Window Scale is used
Steps to reproduce:
* open ristretto like this: `GDK_SCALE=2 ristretto file-to-open.png`
* Ask for Normal Size `Ctrl 0`
Expected at this point:
* Have the picture open pixel-by-pixel as it was
Actually at this point:
* The image will be zoomed in by a factor of 2
If I understand the issue correctly, this is an understandable side-effect of automatic scaling. Yet, it would make sense for ristretto to show the correct zoom level I think. And to make the `Ctrl 0` zoom work correctly. I think the `GDK_SCALE` has to be compensated against (backwards)
Note that just ignoring `GDK_SCALE` is not a desired course of action, because the fact that UI elements are automatically scaled is great actually!
// Scaling is used for e.g. hi-dpi monitors.
issue