[Lazarus] GDB - cannot perform pointer math on incomplete types

[David Emerson]

This error message has often befuddled me when debugging.
I've got a dynamic array, usually a type that I've created, e.g.
type longint_arr = array of longint
I'm using the Watch List and want to inspect one of the elements of such an 
array, e.g. f_list[0]. But I get this error, which I guess comes from GDB.
Is there any way I can coerce it into giving me f_list[0], or even 
f_list[1]?

Thanks,
David