Question: Maybe a bug in MAPLE 2015's Explore ?

Hi, 

Here is the minimal situation that reveals which that could be a (little) bug in the MAPLE 2015 version of Explore.

In the attached file y is a list of numbers and val(r) a procedure that just print the value the rth element of y.
Changing the value of r is done with Explore (of course of no interest at all).
If I define the parameter r as a list ( r=[1..numelems(y)] ), only the value of y[1] is displayed: changing the value of r generates an error.
This doesn(t happen if r is defined as a slider ( r=1..numelems(r) ).

I discovered than the initial instance of Explore defines r as an integer while all the others (due to a change of r) define r as a string.
In the last command of the attached file you will see hjow I have circumvent this problem.

Is it a bug in Explore or does it exist some way to force the values of r to the implicit type they have in r=[$1..numelems(y)] ?

TIA

Download explore.mw