[racket] scrolling panels

On Wed, Jul 13, 2011 at 8:16 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> At Wed, 13 Jul 2011 08:05:30 -0400, Carl Eastlund wrote:
>> On Wed, Jul 13, 2011 at 7:50 AM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
>> > At Wed, 13 Jul 2011 13:20:57 +0400, "Yuriy Kovalev" wrote:
>> >> In release notes for v5.1.1 written: "`racket/gui' library now supports
>> >> scrolling panels". Despite this, I can't find in manual, how to use it. There
>> >> are scrolls for canvas, but not for panels. Where I can see this
>> >> information?
>> >
>> > The `panel%' class and subclasses accept 'hscroll and 'vscroll styles.
>> >
>> > See the next-to-last paragraph at
>> >
>> >  http://docs.racket-lang.org/gui/panel_.html?q=panel%25
>> >
>> > for more information.
>>
>> It appears that panels can only specify whether scrollbars are present
>> or absent, while canvasses have a lot more control over what
>> scrollbars do.  Is there any particular barrier to adding the missing
>> functionality to panels?
>
> Yes, but what would you like to do with panels that doesn't currently
> work?

I don't have any pressing needs at the moment, myself.  But when I
have used canvases with scrollbars in the past, I've pretty much
always fallen back on the manual scrollbar control to get the results
I wanted, because I didn't just have a static image I wanted to scroll
around in.  For instance, in developing the (now long obsolete) object
stepper, I wanted to compute what elements needed to be displayed on
demand based on what area was visible, and I had controls that could
move the scrollbars to bring relevant areas into view.  Can the
current panel setup do things like that?

--Carl