Scaling TightVNC/TigerVNC window on a HiDPI display


I have a HiDPI laptop with a 4K 15.6" display. Having "Xft.dpi: xxx" in .Xresources does the trick for most apps, along with some environment variables like GDK_SCALE and GDK_DPI_SCALE. However, TightVNC and TigerVNC (which neither use Qt nor GTK, I believe) do not seem to respect those values. My VNC display is too small, and resizing the window only increases the canvas size without scaling the actual display. Screenshot:

(or here for the direct link)

How do I scale that window properly?
It looks like, for the time being, there is no support for interface scaling. From

Does it have any interface scaling at all? It seems to use the library FLTK, which does support scaling, and should even read an environment variable FLTK_SCALING_FACTOR. However in practice, changing it does not seem to have any effect. Why is that? Doesn't the client use the scaling features provided by FLTK? Does it override the environment variable setting with some hard-coded value?
No, there is no interface scaling at all. That FLTK setting is unfortunately only for the next version of FLTK. We are still targeting the stable 1.3.x branch of FLTK.

Users on the issue there mention net/remmina and net/vinagre supporting HiDPI display scaling.

For net/tightvnc found this:
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