Our editor relies on the fact that multiple TCastleControl instances work OK. This is turn requires that Lazarus TOpenGLControl (ancestor of our TCastleControl) supports sharing OpenGL resources (CGE caches assume that OpenGL data is shared across contexts). I submitted Lazarus pull requests to fix this:

• for Qt5 (so you can use it now for CGE editor, as a reliable alternative to Gtk2 on Linux/FreeBSD platforms) – qt5: Allow sharing OpenGL context data between instances of TOpenGLControl (!95) · Merge requests · FPC / Lazarus / Lazarus · GitLab.

• for Cocoa (for CGE editor on macOS) – Cocoa: Allow sharing OpenGL context data between instances of TOpenGLControl (!96) · Merge requests · FPC / Lazarus / Lazarus · GitLab. This patch is already applied for the Lazarus version used by our Jenkins to build CGE editor for macOS for our main downloads.