I am not sure, and I don’t think that getting size and position of windows work as you want them. The MainRhinoWindow is a control inside the application window.
Can you explain what you need the application window size and position for so we can understand better what you are trying to do?
The RhinoEtoApp.MainWindow returns on Windows an Eto.Forms.Window that is only a very thin and minimal wrapper around the handle - it isn’t a fully fledged window (you’ll see lots of NotImplementedExceptions if you try to inspect it in the debugger).
I can’t see any provisions for events working so that is out of the question at this time.
Oh, and to get back to one of your requests earlier:
WinForms don’t work on the Mac. If you are planning on getting your plug-in to work on that platform it is probably a good idea to start moving your code to using Eto.Forms now.
@kitjmv have a google for win32controls.cs , you can inject pages, buttons, sliders, whatever you like directly into rhino, locking them to rhino as you move it about by hooking its handle via USER32.DLL, sounds complex, but its really as easy as this below (locking a button into the perspective view, no matter where the perspective view is. I am testing a mac wrapper for it today as well to port this to mac, will feedback how I go.