[pre]
! this is a proc for a dialog which has date-time picker controls,
! one for the date and another for the time of day, respectively
! denoted by IDC_DATE and IDC_TIME; the dialog and its controls were
! created with the standard DevStudio "visual" dialog editor. The month-cal
! control is quite similar, except there are additional messages to set formats
! for the calendar, retrieve date ranges, etc.

INTEGER FUNCTION GetDateProc (hwnd, msg, wParam, lParam) RESULT (res)
!DEC$ IF DEFINED(_X86_)
!DEC$ ATTRIBUTES STDCALL, ALIAS : '_GetDateProc@16' :: GetDateProc
!DEC$ ELSE
!DEC$ ATTRIBUTES STDCALL, ALIAS : 'GetDateProc' :: GetDateProc
!DEC$ ENDIF
IMPLICIT NONE
INTEGER, INTENT(IN) :: hwnd
INTEGER, INTENT(IN) :: msg
INTEGER, INTENT(IN) :: wParam
INTEGER, INTENT(IN) :: lParam

INTEGER :: rval
INTEGER :: hwndControl, hw_time, hw_date
INTEGER :: controlId
INTEGER :: code
TYPE(T_SYSTEMTIME) :: st1, st2

! wrapper function for standard dialog functions
res = DefaultDialogProc (hwnd, msg, wParam, lParam)

SELECT CASE (msg)

! to start the dialog, initialize the members of a SYSTEMTIME structure,
! and send it to both of the DTP controls

CASE (WM_INITDIALOG)

st1 = ! initialize here with starting time and date members; note
! that ALL members must be initialized, even if they will not
! be referenced in the dialog (eg, seconds and milliseconds)
hw_time = GetDlgItem (hwnd, IDC_TIME)
rval = SendMessage (hw_time, DTM_SETSYSTEMTIME, &
GDT_VALID, LOC(st1))
hw_date = GetDlgItem (hwnd, IDC_DATE)
rval = SendMessage (hw_date, DTM_SETSYSTEMTIME, &
GDT_VALID, LOC(st1))
res = 1

CASE (WM_COMMAND)
code = HIWORD(wParam)
controlId = LOWORD(wParam)
hwndControl = lParam

SELECT CASE (controlId)

! dialog concludes: retrieve the two SYSTEMTIME structures,
! pack the ymd values into st1, which will then get returned
! to the calling locus (typically via module-local params which
! are passed back in the dialog's shell routine)
CASE (IDOK)
rval = SendMessage (hw_time, DTM_GETSYSTEMTIME, 0, LOC(st1))
rval = SendMessage (hw_date, DTM_GETSYSTEMTIME, 0, LOC(st2))
st1%wYear = st2%wYear
st1%wMonth = st2%wMonth
st1%wDay = st2%wDay
res = 1

END SELECT

CASE (WM_DESTROY)

END SELECT
END FUNCTION GetDateProc
[/pre]