$choices[ $dialogLB->curselection ] #can't use arr ref as index value
$choices[ @{ $dialogLB->curselection } ] #index value is size of array
$choices[ @$dialogLB->curselection  ] # not an array ref
$choices[ $$dialogLB->curselection  ] # not an scalar ref
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How come this no longer works?

Because you changed your code and added a wantarray perhaps? You are assigning SCALAR context to the return value of your curselection function by using it as an array index. According to Perl it is returning an array ref. This is not a valid index. In your working example you assign ARRAY context to the function call, then that array is evaluated in SCALAR context in the index. Your issue would occur as you say if you had:

sub curselection {
    #
    # was return @array;
    return wantarray ? @array : \@array;
}
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The @$ and $$ issues relate to their precedence being higher than -> so you need @{$a->blah}

cheers

tachyon

"Because you changed your code and added a wantarray perhaps?"

No. curselection is a method of Tk::Listbox, not something written by the OP. Your guess is reasonable, but 5.8.4 Tk::Listbox document still claims that curselection return a list, just as 5.8.0 does.

By the way, the OP has to explain what he was trying to do with that piece of code, the code does look suspicious.

Nope, that returns the size of the list.

The code you give as "your solution":

@index = $dialogLB->curselection;
$what = $choices[@index];
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also uses the size of the returned list as an index.