Anything can be automated, just a matter of how much work you put into it.
For example, while the specific control cannot be recognized as an "open" control with all it's wonderful features, you can probably navigate it using keystrokes and so on. I've had to do that with some old VB grids where, while I could not view the internals, I could navigate with keystrokes and get some validation of the text visible in the grid.
So, what I'd suggest is to look for alternative ways to navigate and utilize the grid. Keep in mind that, for the most part, your goal is not to test the component itself but to test the functionality of the application. So, while you may not be exercising the component fully, you can at least make sure that the application functions.
Robert Martin [Hall of Fame] Please consider giving a Kudo if I write good stuff ----
Why automate? I do automated testing because there's only so much a human being can do and remain healthy. Sleep is a requirement. So, while people sleep, automation that I create does what I've described above in order to make sure that nothing gets past the final defense of the testing group. I love good food, good books, good friends, and good fun.