Well, you create a pic of the background and then draw it.

With the menu, you just draw stuff on it and then have something like A+getkey(1)-getkey(4)->A and then clear the screen and then draw the pic and then draw the curser and then display the screen. Like that you have a moving curser. And to grayscale, exactly the same thing, you just need to draw to bouth screen buffers and update screen with DispGraphr or DispGraphrr   (Radian r)

Maybe you could read throught tutorials?
To draw greyscale:
You need to draw to bouth backup buffers
with pixelon(x,y) you turn a pixel on in the normal buffer
with pixelon(x,y)r    (this is the radian r) you turn a pixel on in the other backup buffer needed for greyscale

That works aswell with all the other drawing things e.g. sprites.

Now, you use DispGraphr (radian r) for 3-level greyscale and Dispgraphrr (radianr) for 4-level greyscale

In three level greyscale:
If i pixel is on in bouth buffers it is black, if it is just on in the normal buffer it is gray

In four level greyscale:
If the pixel is on in bouth buffers it is dark black, if it is just on in the normal buffer it is darkgray, if it is just on in the other buffer it is lightgray

Remember that you need the DispGraph command then in a loop so it seems grey.

Hope I could help you out!

ok, well, what you do:
Draw your pic, store it into a picvariable
[Pic1]->Pic1

Repeat getkey(15)
ClrDraw
Copy(Pic1,L6,768)
//draw curser
DispGraph
Repeat getkey
End
//Change curser possision
End

For Grayscale you do

[Pic1]->Pic1
[Pic2]->Pic2

Repeat getkey(15)
ClrDrawrr
Copy(Pic1,L6,768)
Copy(Pic2,L3,768)
//draw curser
Repeat getkey
Dispgraphr                 //if you want to use 4-level greyscale use instead Dispgraphrr
End
//Change curser possision
End

Well, that's how I would do it!
Important for greyscale is the little loop that repeats till a key is pressed so that it updates the screen often, else it doesn't look grey.

I would still add it to the black/white menu, just coz that's my programming style!