Working with the OpenTK GL Control + MonoGame DesktopGL I can get everything to work by creating a dummy Game to grab the GraphicsDevice… though I only seem to get the “Draw” process to work on one of the controls, the rest will only show the color that the GraphicsDevice was cleared to…
As far as I know, getting a window handle was one of the problems (if not the only real problem) with getting the SwapChainRenderTarget to work with OpenGL functionality, which - because the older MonoGame editions worked with GLControl seems to be the only real reason it was dropped? (Correct me if Im wrong…) But if that was the only issue for it, all that should really be required is to reference a modified version of GLControl from OpenTK (As aside from making the GLControl.cs public (and abstract?) you would really only need to have the SwapChain(for GL) require IWindowInfo and call WindowInfo.Handle to gain this information.)
Sorry If I may be wrong, Ive been all over the place lately, up all night trying to get this GL work around to… actually work… and its been a while since I navigated around all the discussion relating to why this became a problem…
(The old version of this post I noticed I had a little bit of inaccurate information as some of it was based on my memory which has seemed to fail me xD So I edited it.)