Nope.
But as a consolation, you can easily return the palette, by double clicking it's titlebar.
The Navigator has a pin on it, which keeps it visible but this only works when it is not docked, which seems like an outdated feature to me. Maybe a wish would be to include pins to all palettes and have this mean that they will be locked, in your sense of the word.
I know what you mean too. Sometimes a rushed and misdirected click on the arrow tool, hits the x and closes the toolbox!
Cheers,
Link.