Greetings, first of; I’m aware of the restrictions in ActiveX.
I am currently trying to transition from RDM to Royal TS, and as a user with 3 monitors of varying resolutions I have issues with the way ActiveX handles multi-monitor support.
RDM used mstsc if you enabled multi-monitor, which in turn worked excellent with my monitor setup. However, in Royal TS it scales badly.
I also can’t use the same DPI on all my monitors, as that will result in a distracting and frankly annoying work environment. (I have one 1080P, 2K and one 4K monitor).
There are other posts also suggesting a implementation of MSTSC, I am all for this and hope to see it introduced soon.