Bug Notes

Initialization is hard to follow
Conditional statements for tests that could not possibly true.
Invalid setting of flags
Improperly initialized structures before calling SPI_GETHIGHCONTRAST
Obsolete functions being used
Non-NULL values passed to functions that require NULL values
There was code that appended spaces to color scheme and then more code that removed the spaces - looked like 2 programmers worked on it. 
There were loops that would never execute.
Incorrect array sizes passed to many, many functions
Variables declared, initialized but never used
HIGHCONTRAST and MOUSEKEYS did not have ??F_HOTKEYSOUND and ??F_CONFIRMHOTKEY flags set properly
Functions exist that never get called
Incorrect access rights specified when creating a registry key - system would not allow values to be set.
Code fragments repeated throughout
Repeated useless code: x = 5; x = 5;
FilterKeys Slider controls were handled incorrectly - worked on Win95 by coincidence

SPI_?ETKEYBOARDPREF is not on WinNT
SPI_?ETHIGHCONTRAST is not on WinNT
SPI_?ETSERIALKEYS is not on WinNT
// NT doesn't support SSF_INDICATOR but it's not documented or exposed by this Applet.
SOUNDSENTRY.iFSTextEffect is not supported on WinNT
SOUNDSENTRY.iWindowsEffectMSec is not supported on WinNT

MouseKeys:
WinNT only supports: MKF_MOUSEKEYSON, MKF_AVAILABLE, MKF_HOTKEYACTIVE, MKF_HOTKEYSOUND
WinNT does not support: MKF_CONFIRMHOTKEY, MKF_INDICATOR, MKF_MODIFIERS, MKF_REPLACENUMBERS