[M3devel] FW: Win32/ScrollerVBTClass.m3

[Rodney M. Bates]

Olaf Wagner wrote:
> Quoting Randy Coleburn <rcoleburn at scires.com>:
>
>> Olaf:
>>
>> Can you supply me with SRC Report 159 ?
>>
>> The link you give doesn't seem to know how to serve up the report.
I got some kind of permission failure when trying to get it via http:

http://gatekeeper.dec.com/pub/DEC/SRC/research-reports/SRC-159.ps.gz

I manually edited the 'http' to 'ftp' and got it without trouble.  I could
also use ftp to see a listing of the parent directory, with all the SRC
reports.
>
> Strange. I had no problem to download it there.
> I'll CC m3devel in case anybody else cannot get it.
>
> Olaf
>
>> I would like to better understand the locking level pragmas.
>>
>> Regards,
>> Randy
>>
>>>>> Olaf Wagner <wagner at elegosoft.com> 12/14/2009 6:59 AM >>>
>> Quoting Jay K <jay.krell at cornell.edu>:
>>
>>> I keep trying to understand Trestle but I keep failing.
>>> I tried to read the comments explaining how its locking
>>> works and I got lost quickly.
>>
>> Actually the Trestle locking was `verified' after the implementation
>> was finished with the Extended Statical Checker written at that time
>> in Modula-3, too (but reimplemented since then in Java). See
>> SRC report 159, for example here:
>>
>>    http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.36.9943
>>
>> This is where all the locking level pragmas come from.
>>
>>> I suspect that compares well to other GUI libraries
>>> in that they probably just don't do threading well.
>>
>> I always thought that using threads extensively to keep the
>> application
>> responding to user request was one of the strong areas of Testle.
>>
>>> Easy to understand though.
>>>
>>> The Trestle apps are all pretty ugly and oddly behaved.
>>> Granted, I have no "real use" for them. I just exercise
>>> them a bit as test cases.
>>>
>>> I did notice you made the scrollbars look "nice" on Windows.
>>>
>>> The close box is marked "C".
>>> The grow box is marked "G".
>>
>> I grant that making it look better would probably increase the user
>> acceptance. IMO there's no reason not to do that; but there hasn't
>> been
>> anybody interested in working on it yet.
>>
>>> Yuck.
>>>
>>> As I said though, the more I look into Trestle, the more I think
>>> it is implementing a rather complete "windows system" and not
>>> just a library of widgets, nor even widgets + resizing algorithms.
>>> Nor even just widgets + resizing + event routing.
>>>
>>> Like, it seems to also manage clipping, knowing what needs
>>> redrawing, etc.
>>>
>>> But I'm not sure.
>>>
>>> It adds up to a lot of code, is my concern.
>>>
>>> That is good and bad.
>>
>> Yes. But it's a huge project to integrate another GUI library into M3
>> and make it as useful as Trestle.
>>
>> Olaf