When I rdp to xrdp on Lubuntu 18.04 Horizon EDA window stays black, unless another windows covers it forcing refresh of the area underneath. This is probably GTK issue but it’s interesting that it only happens to Horizon EDA window and none others.
This is also happening under noVNC so it’s probably related to type of window that Horizon EDA is using.
I am not sure if related, have not seen this error outside of RDP session:
This is probably due to Horizon EDA being one of the few applications using GtkGLArea. Once there’s a single GL area in a window, gtk. needs to draw the entire window using OpenGL.
You may try the opengl demo from gtk3-demo to verify this. I’ve also seen similar issues on llvmpipe: glitchy rendering on llvmpipe (#747) · Issues · GNOME / gtk · GitLab perhaps it’s actually the same issue as xrdp might have to fall back to software rendering.
Looks like there is a patch for GTK software renderer to address this issue (I did see a related issue that you’ve opened 2 years ago with mesa and GTK).
I suppose, even though not without issues, this could be a way to try Horizon EDA on MacOS: rdp to Linux (or Windows?) VM instance with Horizon EDA and Xrdp installed - thus bypassing OpenGL version requirement.
