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From: David Abrahams (dave_at_[hidden])
Date: 2004-09-22 10:26:45

John Torjo <john.lists_at_[hidden]> writes:

> David Abrahams wrote:
>> Matt S Trentini <matt_trentini_at_[hidden]> writes:
>>>John Torjo wrote:
>>>>Could you elaborate a bit? What do you think is the window handle
>>>>limit under win32?
>>>I think that perhaps Mathew is talking about the GDI object limit. At
>>>least under Windows 2000 and earlier versions (I'm not sure about XP)
>>>there is a firm limit of 16K handles that can be allocated system wide
>>> -
>>>regardless of your particular specs (ie adding memory does not
>>>help). When this limit is reached weird stuff [1] happens which can
>>>only be fixed by a reboot.
>>>Any object that allocates a handle under Windows (pens, brushes, dc's,
>>>etc) consume those resources and if you've got a graphically intense
>>>GUI using a greedy GUI library (ie one that holds it's handles for a
>>>long duration) that limit isn't too hard to break.
>> Yes, IIRC, that's why a spreadsheet implemented with a Window per
>> cell
>> will have a very small maximum size, and why ultimately, any robust
>> window framework under Win32 has to have an abstraction layer that
>> makes the issue of whether or not there's a real "windows window"
>> running the show in any given pane disappear.
> Why not just use an existing list control or grid?

You're not getting it; that's just one way to run out of handles.
What if the existing list/grid controls don't do what I want?

Dave Abrahams
Boost Consulting

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