Scaling user interface for HiDPI displays

[Jarno Suni]

Firstly, I think the Custom DPI setting is misleading term in Appearance settings, as display's resolution (or display's physical size) do not change by the setting. It could be named as text scaling factor or something. Besides, naming it as Custom DPI setting is confusing with monitors that have different DPI for vertical and horizontal dimension:
https://bugzilla.xfce.org/show_bug.cgi?id=10633
What I miss is ability to use different scaling factor for different monitors, when using extended desktop since text on some high DPI monitor might be hard to read from the same distance than you use a low DPI monitor from. I think ideally user interface elements would have the same effective physical size in both monitors even if the monitors have different physical dimensions and display modes, if user uses both monitors from the same distance. Maybe better place to set monitor specific scaling factor would be in xfce4-display-settings instead of Appearance settings.
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Jarno Suni - http://iki.fi/8/