A user might want to specify a DPI for their Windows connection. This is currently not possible.
This was implemented in rdesktop and integrated into ThinLinc with the vendordrop in r32951. It is now possible to specify the DPI using the geometry flag:
tl-run-rdesktop -g 1024x768@240
Works well. Note however that this API isn't supported for Windows servers older than server 2012.
Not mentioning in release notes due to the fact that the rest of ThinLinc lacks support for high DPI / scaling. See bug 5273.