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If GNOME enters HiDPI mode with 1440 vertical pixels "
Could you please explain "If"? The question is: does* it use such simple logic? Do you know about it? That would be ridiculous IMO. If not, it would be nice if someone could elaborate the logic/algorithm Gnome uses.
It should at least depend on DPI, and there should further be a 'scaling'/zoom' (at least globally but preferably also per_application) user setting. A good quality monitor is usable with higher DPI than a poorer one. On an 27" monitor, for instance, 1920*1440 is actually a somewhat low DPI. Win7 (and various Linuxes running virtualized) works fine on my stationary here with a 27" monitor (this one: http://www.samsung.com/ca/consumer/office/monitors/led/LS27B970DS/ZC) with 2560*1440 resolution. I bought this monitor in order to work in 3-4 application (all reasonable sized) simultaneously. I will not accept that some stupid Window Manager *thinks that I am better off* with 1280*720 or whtever similar. I really don't hope this is the case.
There are also personal preferences. Some people like it big and some people like it small.
-- Peter