Dragging Transparent NSWindow with parent NSOpenGLView

As previously discussed, I'm using a transparent NSWindow containing
an NSSearchField so that I can do search over my NSOpenGLView-based
app.

I'm having problems constraining the transparent NSWindow's position
while the parent  NSOpenGLView is being moved. Overloading
-windowWillMove and -windowDidMove, I can only reposition everything
*before* and *after* the fact, which looks pretty bad.

Is there a way to either track the main window while it is being moved
or to automatically define a NIB-style constrained layout for floating
NSWindows?

BTW, NSOpenGLView does not allow sub-views, so a creative solution has
to be found to get around that.

Thanks,

-- 
- Nick -