It might be a lack of multimonitor support in the Haiku itself. When I boot my multimonitor system up, the Haiku boot screen icons are mirrored to both the 1080p HDMI output and the 900p DVI-D output; after the rocket icon lights up, both screens turn white; then the 1080p screen shows the Haiku screen while the 900p screen stays white.
What does this have to do with RDP?
It might have a common cause with the white screen.
No; not at all. A white screen on real hardware is usually caused by the video driver failing to set up the hardware correctly. As a result, nothing is displayed, and this can end up either white or black depending on the display technology.
FreeRDP has nothing like that. Also we’re talking about a remote desktop client here, so it’s about showing the display from anoter system inside Haiku. Which does not involve any of Haiku drawing stack at all, except getting a bitmap from the network and putting it on a window.
The problem was actually with rfx/gfx, I accidentally forced bpp instead of allowing the client/server to handshake and the window is no longer white. I can see the video.
The problem is that without rfx/gfx is incredible slow, so Remmina works best even though it still has some minor bugs with keyboard layout