Nope. Scaling is supported by Gtk3 (but you can only scale by integer - 2x, 3x) and Qt5. A lot of apps are still using Gtk2 and Qt4. It is a mess. I wish I had an FHD display instead of WQHD.
Well, if you use the gtk3 hidpi settings, yes. However, if you disable the HiDPI, scale it to 1x, and then set the font "Scaling Factor" in gnome-tweak-tool to something else, say, 1.25, (a non-integer!) it works great!
For Gtk3 apps it works reasonably well (it scales text, but not buttons, widgets, etc). There's nothing you can do with Gtk2, Qt4 apps though (other than changing font size).
Not without having fuzzy text. I explained it once on reddit:
> Is there any difference between FHD monitor and WQHD in FullHD mode?
Yes, there is. WQHD is 2560x1440 pixels. If you set your resolution to half that (in width and height) it is 1280x720 (2560/1280=2, 1440/720=2). In that case every software pixel is represented by 4 physical pixels (2x2) and we are fine. If you set resolution to 1920x1080 (FHD): 2560/1920 = 1.33, 1440/1080=1.33 . And we know there is no 1.33 physical pixel! So the image becomes distorted and looks bad.
rMBP13 has physical resolution 2540x1600 (i.e. 1280x800 x 2). The control panel offers resolutions 2880x1800 (1440x900 x 2) and 3360x2100 (1680x1050 x 2), that the GPU will scale down to 2540x1600. And these resolutions look good and sharp.
In fact so good, that the final resolution depends only on what physical size / working space you prefer, not which one looks good and which one doesn't.
Keep in mind that Apple claims they developed custom scaling algorithms to handle these downscale modes, so a PC user doing the same thing using GPU drivers might not get as good results.
Not that I know of. Screen can be scaled with xrandr (on X11), but that significantly decreases performance. There's a chance of making it work on Wayland (modern replacement for X11) in the future.
Nope. Scaling is supported by Gtk3 (but you can only scale by integer - 2x, 3x) and Qt5. A lot of apps are still using Gtk2 and Qt4. It is a mess. I wish I had an FHD display instead of WQHD.