LIB-PM-ComboBoxSupport

Combo Box Support library for OS/2 Presentation Manager. Provides two helper routines that simplify initializing PM combo boxes: populating the list and setting an initial selection.

Originally written by Dave Briccetti in January 1990 as a 16-bit OS/2 PM library. Ported to 32-bit OS/2 (ArcaOS / Warp 4) using OpenWatcom 2.0.1.

API

USHORT EXPENTRY InitComboBox(
    HWND    hwnd,              // Owner window handle
    SHORT   idCombo,           // Combo box control ID
    PSZ    *apszInit,          // NULL-terminated array of string pointers
    SHORT   InitialSelection   // Index to pre-select, or ICB_NOSELECTION
);

USHORT EXPENTRY InitComboBoxFromRcStrings(
    HAB     hab,               // Anchor block handle
    HWND    hwnd,              // Owner window handle
    SHORT   idCombo,           // Combo box control ID
    SHORT   cStrings,          // Number of resource strings to load
    SHORT   aidStrings[],      // Array of resource string IDs
    SHORT   cbStringMax,       // Maximum string length
    HMODULE hmodResource,      // Resource module handle, or 0 for current EXE
    SHORT   InitialSelection   // Index to pre-select, or ICB_NOSELECTION
);

ICB_NOSELECTION (defined in h/combosup.h) leaves the combo with no initial selection.

Directory Layout

src/            DLL source (combosup.c)
h/              Public header (combosup.h)
sample/         Sample PM application (combosmp.c, combosmp.h, combosmp.rc)
dll/            Built DLL and map file (build output)
lib/            Import library combosup.lib (generated during build)
obj/            Intermediate object files (build output)
doc/            Documentation
makefile.wat    OpenWatcom wmake build file
compile.cmd     Build script

Building

Requires OpenWatcom 2.0.1 with the environment configured (WATCOM variable set). Run from the project root on ArcaOS:

compile.cmd

Outputs:

File	Description
dll\combosup.dll	32-bit PM combo box support DLL
lib\combosup.lib	Import library for linking
sample\combosmp.exe	Sample PM application

Runtime

combosup.dll must be on the LIBPATH (or in the same directory as the EXE) when running any application linked against combosup.lib.

32-bit Port Notes

• halloc/hfree (16-bit huge-model allocators) replaced with malloc/free.
• EXPENTRY expands to _System in 32-bit os2.h; export names are mixed-case (InitComboBox, InitComboBoxFromRcStrings).
• Window procedure msg parameter corrected from USHORT to ULONG, as required by the 32-bit PFNWP signature.
• WinQuerySysValue return values stored as LONG instead of SHORT to avoid truncation on large displays.
• Build system replaced: Microsoft C 6 / LINK / RC → OpenWatcom wcc386 / wlink / wrc.
• option implib= in the wlink step auto-generates combosup.lib as a side effect of linking the DLL (no separate librarian step needed).

License

Public Domain. Original code by Dave Briccetti (1990).