Well I'll be... So you're right. My problem was that I had changed the
..BackColor to something different and then set it back to "Windows" using
the Properties window at design time. Once you do that, even though you set
the color back to Windows, setting .Enable=False no longer grays the box.
You have to hi-lite the .BackColor property in the Properties window and hit
delete. It'll still say "Windows" (no longer Bold) but then .Enable=False
will gray the box. Strange.
Thanks for making me take another look, I probably would never have figured
that out. I was already setting it's .BackColor to
Color.FromArgb(128,128,128) or Color.FromKnownColor(KnownColor.Window) when
the UserControl's EnableChanged(...) event fired.