Re: Widget Event_Pro question

On Mar 31, 3:45 pm, David Fanning <n...@[EMAIL PROTECTED]
> wrote:

Hello once again,

I'm now trying to find the best way to tell widget A how many copies
of widget B are open, and what their IDs are, so that widget A knows
what to kill when the user presses the 'Graph Deletion' button. I'm
doing this by passing a pointer to an array around my top-level UVAL
structure, and concatenating the new graph widget IDs onto the array
as they get created, and then removing these IDs when the widget gets
killed.

I need to define this array before any instances of widget B are open.
Can I use a value of [-1L] for this? Or is -1 a valid widget ID number
that might cause problems later if IDL decides to label one of my
widgets -1 at some point?

Regards,

Chris