* note: to reverse the system colors back to normal 
* release the oColorTest variable
 
PUBLIC oColorTest As TColorTest
oColorTest = CREATEOBJECT("TColorTest")
oColorTest.ChangeColors
* end of main
 
DEFINE CLASS TColorTest As Session
PROTECTED ColorMask, SavedColors, NewColors
 
PROCEDURE Init
    THIS.declare
 
PROCEDURE ChangeColors
#DEFINE COLOR_SCROLLBAR 0
#DEFINE COLOR_ACTIVECAPTION 2
#DEFINE COLOR_WINDOW 5
#DEFINE COLOR_WINDOWFRAME 6
#DEFINE COLOR_MENUTEXT 7
#DEFINE COLOR_WINDOWTEXT 8
    * colors for these two elements are to be 
    * changed and eventually restored back
    THIS.ColorMask = num2dword(COLOR_WINDOW)+;
        num2dword(COLOR_ACTIVECAPTION)
 
    * the original colors are saved in the class property
    THIS.SavedColors = num2dword(GetSysColor(COLOR_WINDOW))+;
        num2dword(GetSysColor(COLOR_ACTIVECAPTION))
 
    * changing the colors
    THIS.NewColors = num2dword(RGB(128,192,230))+;
        num2dword(RGB(192,0,192))
 
    = SetSysColors(2, THIS.ColorMask, THIS.NewColors)
 
PROCEDURE Destroy
* making sure that upon releasing the instance
* of the class all colors are restored back
    THIS.RestoreColors
 
PROCEDURE RestoreColors
    = SetSysColors(2, THIS.ColorMask, THIS.SavedColors)
 
PROCEDURE declare
    DECLARE INTEGER GetSysColor IN user32 INTEGER nIndex
 
    DECLARE INTEGER SetSysColors IN user32;
        INTEGER nElements, STRING lpSysColor,;
        STRING lpColorValues
 
ENDDEFINE
 
FUNCTION num2dword(lnValue)
#DEFINE m0 0x0000100
#DEFINE m1 0x0010000
#DEFINE m2 0x1000000
    IF lnValue < 0
        lnValue = 0x100000000 + lnValue
    ENDIF
    LOCAL b0, b1, b2, b3
    b3 = Int(lnValue/m2)
    b2 = Int((lnValue - b3*m2)/m1)
    b1 = Int((lnValue - b3*m2 - b2*m1)/m0)
    b0 = Mod(lnValue, m0)
RETURN Chr(b0)+Chr(b1)+Chr(b2)+Chr(b3)