I used to do VB, and what you are trying to do should be simple. In VB, you can create an array of combo boxes, and the first argument to ComboBox_Change would be the index of the current combo box. This is standard Windows functionality.

Sadly (in your case), control arrays are not made available to the Perl programmer through Win32::GUI. When the ComboBox_Change event is called, it is called with no arguments at all.

To make it work, I would create an anonymous sub reference like so:

foreach my $x (0..$count){
    $SUB = accounts[$x]."ComboBox_Change";
    *$SUB = sub { ComboBox $x };
}
[download]

Then in sub ComboBox, put

my $index = shift;

This will pass the array index of the changed combo box to the ComboBox sub, which you can use with comboboxes[$index]

Note: This will not work with strict unless you use no strict qw/refs/;, but since Win32::GUI itself won't run properly without no strict qw/subs/; this shouldn't trouble you too much.