This is the text, extracted from a presentation for Palm OS Programming Gotchyas and Pitfalls. I don't use Adobe and I wanted a textual reference instead of printing out slides, so I did this. View the original information at PalmSource, number 106.

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Confusing Form Object ID with Object Index
pBtn = FrmGetObjectPtr(MainOKButton);

• Most Form Manager routines need object index
• Compiler can't catch: both are type UInt16
• Typical error messages:
  • Object not found in form
  • Index out of range
• Solution: check API parameters carefully and use FrmGetObjectIndex()

Correct ID, Wrong Resource
pLogo = DmGetResource(bitmapRsc, 10004);

• If DmGetResource() can't find match in the last opened resource database, continues search through resource chain
• Solution
  • Use Console opened command to display theresource chain
  • Don't use resource IDs <= 128 or >= 10000
  • Use DmGet1Resource()

Apps Must Use appl as Database Type

• Runs when you debug, but does not show up in Launcher
• Launcher only displays icons for resource databases of type appl
• App built with a different type can run, but must be launched via code
• Set in PalmRez post linker panel

Popup Lists

• Assign list object ID to trigger
• Check for popSelectEvent
• Override default behavior of popSelectEvent if list items are not defined
  • In resources
  • By using LstSetListItems()
• Return true from event handler

FrmCopyTitle & FrmCopyLabel

• These calls copy a string to a buffer
• Buffer size is determined by size of label or title defined in resources
• Solution 1: Make placeholder label/title "big enough" to hold anticipated strings
• Solution 2: Use FrmSetTitle() for forms
• Solution 3: Use text fields instead of labels if you need to change at runtime

Common C/C++ Problems

• Learn C before learning Palm OS APIs
• Pointers and data type promotion
• Example
  • Char *p;
    StrCopy(p, "Ooops");
    P = MemPtrNew(60 * 1024);
    

Standard C Libraries vs. Palm OS APIs

• Use String and Memory Managers
  • Smaller app footprint
  • Support for multibyte character sets
• However, check API parameters carefully
  • StrPrintF is almost the same as sprintf
  • MemSet parameters switched from memset
• Exception handling
  • Use Error Manager instead of C++ exceptions
  • ErrTry, ErrCatch, etc.

Form Drawing

• Call FrmDrawForm before drawing on form
  • Problems with modal dialogs and "save behind" bit
  • Debug ROMs will catch
  • Can use WinScreenLock to improve performance
• Beware functions that draw immediately
  • FldDrawField, LstDrawList, etc.

Form Updating

• Default frmUpdateEvent calls FrmDrawForm()
  • Erases form
  • Draws form border
  • Draws form objects
  • But not old-style gadgets
• Custom drawing not updated unless you handle the event yourself
• Use extended gadgets to automate
• If you do handle frmUpdateEvent return true to stop system from handling it after you

Text Fields

• Don't use FldGrabFocus()
  • Use FrmSetFocus()
  • Call FrmSetFocus() after FrmDrawForm()
• Use PrvSetFieldText() from NetSample sample project
  • Does all the right things
  • Avoids all the standard difficulties
  • Supports immediate/delayed update and appending

Database Names and Creator Codes

• Creator codes should be unique
  • Benefits your customers if unique
  • Automates clean-up of device when deleting
  • Register code before coding starts
  • www.palmos.com/dev web form
• Database names must be unique
  • Remember, apps are databases also
  • Use form "AppName-Code"

Palm OS Data Structure Access

• Don't access UI data structure fields directly
• Use accessor functions
  • FrmGetFormId(), LstGetSelection(), etc.
  • New accessors in SDK 4.0 Update 1
• Good way to prepare for Palm OSŪ Version 5
• Palm OS Emulator reports (non-fatal error)
• Catch in compiler
  • #define DO_NOT_ALLOW_ACCESS_TO_INTERNALS_OF_STRUCTS
    #include <PalmOS.h>

Database Searching

• DmFindSortPosition()
  • Design: maintain sort order when adding records
  • Returns index after any matching records
• When used to find records:
  • If index > 0, compare previous record
  • If record matches, you found search target
  • If record does not match, search target is not in database

Global Variables

• Not accessible if app is not active
  • Find, receive beam, alarms, etc.
• Global data not always obvious
  • String constants
  • Smart code model intra-segment jumps
  • Access at end of long function call chain
• Use #pragma warn_a5_access on
• Use "PC-Relative strings" options

Error Avoidance

• Require function prototypes
• Turn on all warnings and errors
• Use DO_NOT_ALLOW_ACCESS_TO_INTERNALS_OF_STRUCTS
• Use assertions
• Use POSE and debug ROMs

POSE and Debug ROMs

• Palm OS Emulator will catch numerous errors
  • Memory leaks, data structure access, stacko verflow, low memory access, ...
  • Gremlins and new minimize feature automate the hunt
• Debug ROMs check for invalid parameters
  • Range checking, forced update events, etc.
• Always use the latest POSE build
• Test using ROMs for minimum and latest versions of Palm OS

Suggestions

• Palm OS® Essentials course
  • Lots of lab time
  • Developer instructors
  • Terrific sample applications with source
• Palm OS Recipes
  • Step-by-step solutions to common problems
  • Under Documentation link on www.palmos.com/dev
• Sample code
  • Use CodeWarrior Find feature, grep, etc.
• Third-party books