Thanks for the icon editor suggestions. I wasn't able to find anything with Google except XN Resource Editor, which seems to fail completely, at least wrt creating icons.
I downloaded both editors you recommended, and they seem to do the job properly. At least the icon for the icon file itself looks right, and I can open the icon file with both editors and see all 9 images with the proper resolutions and color depths.
But the icon still doesn't look right after creating with NSIS. The old gray scale icon shows up instead of the color one. For example, I create the QuickLaunch icon with
CreateShortcut $QUICKLAUNCH\$(^Name).lnk "$INSTDIR\ec.exe" "" "$INSTDIR\ec_icon.ico"
after having put the icon file in the install dir via
SetOutPath $INSTDIR
File "ec_icon.ico"
But then the QL icon is gray scale. This happens with start menu icons as well.
I thought perhaps I need to supply an icon index number in the CreateShortcut command, but I don't see any index numbers identifying the icon images with either editor. I tried using 1, 2,3...9 for icon indices, but when I do that NSIS fails to find the icon altogether.
For some reason NSIS seems to be causing the icon to be rendered with 1-bit color depth. I followed prospec's suggestion and manually configured a QuickLaunch item to point to the same icon file, and then it's rendered properly in the QuickLaunch tray. I also tried the following for creating the QL shortcut
CreateShortcut "$SMPrograms\$StartMenuGroup\$(^Name).lnk" "$INSTDIR\ec.exe" "" "ec_icon.ico"
so I point directly to the icon file instead of extracting it from the installer executable. In this case I get the gray scale icon image as well. So I seem to be close, but I remain flummoxed.
BTW, I posted the new version of the icon file, created with IcoFX,
here