Dec 97 - Macintosh Q and A
Volume Number: 13
Issue Number: 12
Column Tag: develop
Macintosh Q & A
by Apple Developer Support Center
White Backgrounds for Dialog editText Items
Q. I would like to have a colored background for my dialog box but I would like the
TextEdit fields in my dialog box to be white. Is this possible to do? Is there some
sample code available?
A. Generally speaking, this coloring is achieved via resources, not code. In addition to
the dctb' resource, you need to create an 'ictb' resource.
To download a sample of an application using this kind of resource go to
http://devworld.apple.com/dev/qa/tb/tb3.html.
The 'ictb' resource is documented on page 6-76 and starting again on page 6-158 of
Inside Macintosh: Macintosh Toolbox Essentials. The best way I know of to create and
edit 'ictb' resources is with Resorcerer, but you can also create them with a '.r' file
compiled by either MPW's Rez or the Metrowerks CodeWarrior equivalent.
Here are some references to web sites for the aforementioned tools:
Resorcerer:
http://www.mathemaesthetics.com/
ETO (incl. Rez):
http://www.devtools.apple.com/eto/
CodeWarrior:
http://www.metrowerks.com/
If this response has failed to adequately address a question or has raised more
questions than it answered, please feel free to let us know and we'll try again.
Pete Gontier
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OTScheduleDeferredTask When Task Running
Q. What happens when you use OTScheduleDeferredTask to schedule a task that is
running?
A. The "Open Transport Client Note" mentions that OTScheduleDeferredTask returns
false when you attempt to schedule a task that is already scheduled, but it doesn't say
anything about what happens if the task is running. It turns out that a task that is
running is not consider to be scheduled, so OTScheduleDeferredTask will successfully
reschedule it.
Quinn "The Eskimo!
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Gestalt Values for Recent Macintosh Models
Q. What are the 'mach' gestalt values for the recent Macintosh models?
A. Recently, we announced the following new Macintosh models:
PowerBook 2400
The following list includes the 'mach' gestalt selectors for these and other Macintosh
systems which are not included in the Gestalt.h header file which is part of the
"Universal Interfaces 2.1 in MPW Latest" on ETO #22.
• gestaltPerforma5300 = 41; { Macintosh Performa 53xx }
• gestaltPowerMac5260 = 41; { Power Macintosh 5260/100 }
• gestaltPerforma6300 = 42; { Macintosh Performa 63xx, except 6360 }
• gestaltPerforma6360 = 58; { Performa 6360 }
• gestaltPerforma6400 = 58; { Performa 6400 }
• gestaltPowerMac9600 = 67; { Power Macintosh 9600
• gestaltPowerMac7600 = 68; { Power Macintosh 7600 }
• gestaltPowerMac8600 = 69; { Power Macintosh 8600 }
• gestaltPowerMac5400 = 74; { Power Macintosh 5400/120}
• gestaltMacLC580 = 99; { Macintosh LC 580 }
• gestaltPerforma580 = 99; { Macintosh Performa 580 }
• gestaltPowerMacLC475 = 104; { Mac LC 475 & PPC Processor Upgrade
Card }
• gestaltPowerMacPerforma47x = 104; { Performa 47x & PPC Proc
Upgrade Card }
• gestaltPowerMacLC575 = 105; { Mac LC 575 & PPC Processor Upgrade
Card }
• gestaltPowerMacPerforma57x = 105; { Performa 57x & PPC Proc
Upgrade Card }
• gestaltPowerMacQuadra630 = 106; { Quadra 630 & PPC Processor
Upgrade Card }
• gestaltPowerMacLC630 = 106; { Mac LC 630 & PPC Processor Upgrade
Card }
• gestaltPowerMac7300 = 109; { Power Macintosh 7300 }
• gestaltPowerMacQuadra700 = 116; { Quadra 700 & Power PC Upgrade
Card }
• gestaltPowerMacQuadra900 = 117; { Quadra 900 & Power PC Upgrade
Card }
• gestaltPowerMacQuadra950 = 118; { Quadra 950 & Power PC Upgrade
Card }
• gestaltPowerMacCentris610 = 119; { Centris 610 & Power PC Upgrade
Card }
• gestaltPowerMacCentris650 = 120; { Centris 650 & Power PC Upgrade
Card }
• gestaltPowerMacQuadra610 = 121; { Quadra 610 & Power PC Upgrade
Card }
• gestaltPowerMacQuadra650 = 122; { Quadra 650 & Power PC Upgrade
Card }
• gestaltPowerMacQuadra800 = 123; { Quadra 800 & Power PC Upgrade
Card }
• gestaltPowerBook3400 = 306; { Macintosh PowerBook 3400 }
• gestaltPowerBook2400 = 307; { Macintosh PowerBook 2400 }
• gestaltPowerBook1400 = 310; { Macintosh PowerBook 1400 }
• gestaltPowerMac5500 = 512; { Power Macintosh 5500 }
• gestalt20thAnnivMac = 512; { Twentieth Anniversary Macintosh }
• gestaltPowerMac5500 = 512; { Power Macintosh 5500 }
• gestaltPowerMac6500 = 513; { Power Macintosh 6500 }
• gestaltPowerMac4400 = 515; { Power Macintosh 4400 }
Note: To distinguish the Twentieth Anniversary Macintosh from the Power Macintosh
5500, make a secondary Gestalt selector call to the selector 'bxid'. The response for a
Twentieth Anniversary Macintosh will be 0x0000302B
Rich Kubota
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Find Desktop Folder
Q. The General control panel (GCP) in 7.6, 7.6.1 and 8.0 has the document options:
Last folder, Application set folder, and Documents folder. How can my application
determine where this folder is?
A. The General control panel (GCP) patches FindFolder so it will return the correct
document folder given the current GCP options. Pass FindFolder a folderType of 'docs'.
One quick note: Because the GCP patches FindFolder, the createFolder option doesn't
work. If the folder doesn't exist you won't get an error and it won't be created. You have
to write code to determine if the folder actually exist: if it doesn't, you'll have to create
it yourself.
George Warner
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Q. When I am debugging my application MemError() always returns noErr. What's
wrong with MemError()?
A. Nothing, if you are debugging your application with a high level debugger. High
level debuggers often call Memory Manager routines while stepping through your code.
When a Memory Manager routine is called, it sets MemError() and in this case, the
debugger's memory request was successful (it returned noErr) and cleared your
application's MemError() result.
The solution to this problem is often just to not step over Memory Manager calls and
the call to MemError(). If you put a break point just after the MemError() call, you
usually get the correct error -- the one your application would see if it wasn't
running in the debugger.
The other option is to use a low level debugger such as MacsBug to debug your memory
allocation problems.
As a general rule your application should check the value of the handle or pointer
returned by NewHandle, NewPtr, etc: and if it is nil, you should call MemError() for
an error number. Just calling MemError() without checking the value of the
handle/pointer is not a good idea.
Mark Cookson