Ok, I finally have a full answer and will update the ProAudio Seed Release Notes accordingly. Please check them regularly.
Windows opened by the plugin might have a subtle magenta tinting. This is security feature, not a bug. It avoids that malicious code can open a window which overlays system windows. There are a couple of ways to avoid this tinting:
- Make the window less transparent (75% or more opacity will avoid this tinting)
- Call -[NSWindow addChildWindow:…]. This will confine the magenta to the remote view, which spawns the child.
- Use a standard window to obtain rounded corners without using a transparent background color.