[M3devel] FW: Win32/ScrollerVBTClass.m3

[Olaf Wagner]

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.

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
-- 
Olaf Wagner -- elego Software Solutions GmbH
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