User defined key going to straight to a program

[matalog]

I tired this, to remove the need to press enter, after a key assigning program, returning a program name as a function:

Code:

KEY K_Sin()
BEGIN
 Input(A,"Number","Number: ",0,0);
 Return A;
END;

But it doesn't work as expected. Depending on the number entered in the input box, the program will return different things, I once (with 78 input) got it to return a square symbol with circle inside, and got it to return Sin() (with 238 or something close input. Both times, I had User Input activated, and my program ran upon clicking Sin() key. Inputting 83 will bring up the Lists menu, and 84 will return curly brackets.

What I am describing is in textbook entry mode.

Were user keys assignments not designed to work like this, is it considered a bug?

Is there a correct way to run a user program with a single button press (not followed by Enter), that will allow the Returned number to go on the calculator stack?