Thanks Mike, That's more or less what i'd like to do, but this behavior does not seem to transpose well into Manipulate expressions.. Or at least i did not manage to make it work.

Let's say we want to use a sequence in this Manipulate object, and use 1,2,3 as an input instead of {1,2,3}. How could we do it?

I'm taking a guess that you want to pass separate scalars to a function instead of putting those scalars into a list.

The Wolfram has the concept of sequences which can help. And fortunately, it is easy to switch between sequences and lists. For example, if I define a function as:

f[x : ___] := List[x];
f[x_List] := x;

Then, I can call this function with either:

f[1, 2, 3];
f[{1, 2, 3}];

And get the same result: {1, 2, 3}

If this isn't what you are talking about, please provide some more info.

THANKS