Screensaver not configuring properly

The problem: Whenever I compile and run the screensaver, and open the configure dialog, and try to move the scrollbar, the scrollbar does not move. What is wrong??

I know this is a lot of code, but I think the problem lies in the WM_HSCROLL message or in the ID_OK message.

Code:

---

//main.c
#define MINVEL  1                // minimum redraw speed value
#define MAXVEL  10                // maximum redraw speed value
#define DEFVEL  5                // default redraw speed value
#include <stdio.h>
#include "resource.h"
LONG    lSpeed = DEFVEL;          // redraw speed variable

extern HINSTANCE hMainInstance;  // screen saver instance handle

CHAR  szAppName[80];            // .ini section name
CHAR  szTemp[20];                // temporary array of characters
CHAR  szRedrawSpeed[ ] = "Redraw Speed";  // .ini speed entry
CHAR  szIniFile[MAXFILELEN];    // .ini or registry file name
UINT i=0;
BOOL WINAPI ScreenSaverConfigureDialog(hDlg, message, wParam, lParam)
HWND    hDlg;
UINT    message;
WPARAM    wParam;
LPARAM    lParam;
{
    static HWND hSpeed;  // handle to speed scroll bar
    static HWND hOK;      // handle to OK push button

    switch(message)
    {
        case WM_INITDIALOG:

            // Retrieve the application name from the .rc file.
            LoadString(hMainInstance, idsAppName, szAppName,
                      80 * sizeof(TCHAR));

            // Retrieve the .ini (or registry) file name.
            LoadString(hMainInstance, idsIniFile, szIniFile,
                      MAXFILELEN * sizeof(TCHAR));

            // TODO: Add error checking to verify LoadString success
            //      for both calls.

            // Retrieve any redraw speed data from the registry.
            lSpeed = GetPrivateProfileInt(szAppName, szRedrawSpeed,
                                          DEFVEL, szIniFile);

            // If the initialization file does not contain an entry
            // for this screen saver, use the default value.
            if(lSpeed > MAXVEL || lSpeed < MINVEL)
                lSpeed = DEFVEL;

            // Initialize the redraw speed scroll bar control.
            hSpeed = GetDlgItem(hDlg, ID_SPEED);
            SetScrollRange(hSpeed, SB_CTL, MINVEL, MAXVEL, FALSE);
            SetScrollPos(hSpeed, SB_CTL, lSpeed, TRUE);

            // Retrieve a handle to the OK push button control.
            hOK = GetDlgItem(hDlg, ID_OK);

            return TRUE;

        case WM_HSCROLL:

            // Process scroll bar input, adjusting the lSpeed
            // value as appropriate.
            switch (LOWORD(wParam))
                {
                    case SB_PAGEUP:
                        --lSpeed;
                    break;

                    case SB_LINEUP:
                        --lSpeed;
                    break;

                    case SB_PAGEDOWN:
                        ++lSpeed;
                    break;

                    case SB_LINEDOWN:
                        ++lSpeed;
                    break;

                    case SB_THUMBPOSITION:
                        lSpeed = HIWORD(wParam);
                    break;

                    case SB_BOTTOM:
                        lSpeed = MINVEL;
                    break;

                    case SB_TOP:
                        lSpeed = MAXVEL;
                    break;

                    case SB_THUMBTRACK:
                    case SB_ENDSCROLL:
                        return TRUE;
                    break;
                }

                if ((int) lSpeed <= MINVEL)
                    lSpeed = MINVEL;
                if ((int) lSpeed >= MAXVEL)
                    lSpeed = MAXVEL;

                SetScrollPos((HWND) lParam, SB_CTL, lSpeed, TRUE);
            break;

        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case ID_OK:

                    // Write the current redraw speed variable to
                    // the .ini file.
                    //hr = StringCchPrintf(szTemp, 20, "%ld", lSpeed);
                    wsprintf(szTemp, "%ld", lSpeed);
                    //if (SUCCEEDED(hr))
                        WritePrivateProfileString(szAppName, szRedrawSpeed,
                                                  szTemp, szIniFile);

                case ID_CANCEL:
                    EndDialog(hDlg, LOWORD(wParam) == ID_OK);

                return TRUE;
            }
    }
    return FALSE;
}

BOOL WINAPI RegisterDialogClasses(hInst)
HANDLE  hInst;
{
    return TRUE;
}

LONG WINAPI ScreenSaverProc(hwnd, message, wParam, lParam)
HWND  hwnd;
UINT  message;
WPARAM wParam;
LPARAM  lParam;
{
    static HDC          hdc;      // device-context handle
    static RECT        rc;      // RECT structure
    static UINT        uTimer;  // timer identifier

    switch(message)
    {
        case WM_CREATE:

            // Retrieve the application name from the .rc file.
            LoadString(hMainInstance, idsAppName, szAppName, 80 * sizeof(TCHAR));

            // Retrieve the .ini (or registry) file name.
            LoadString(hMainInstance, idsIniFile, szIniFile, MAXFILELEN * sizeof(TCHAR));

            // TODO: Add error checking to verify LoadString success
            //      for both calls.

            // Retrieve any redraw speed data from the registry.
            lSpeed = GetPrivateProfileInt(szAppName, szRedrawSpeed,
                                          DEFVEL, szIniFile);

            // Set a timer for the screen saver window using the
            // redraw rate stored in Regedit.ini.
            uTimer = SetTimer(hwnd, 1, lSpeed * 1000, NULL);
            break;

        case WM_ERASEBKGND:

            // The WM_ERASEBKGND message is issued before the
            // WM_TIMER message, allowing the screen saver to
            // paint the background as appropriate.

            hdc = GetDC(hwnd);
            GetClientRect (hwnd, &rc);
            FillRect (hdc, &rc, GetStockObject(BLACK_BRUSH));
            ReleaseDC(hwnd,hdc);
            break;

        case WM_TIMER:

            // The WM_TIMER message is issued at (lSpeed * 1000)
            // intervals, where lSpeed == .001 seconds. This
            // code repaints the entire desktop with a white,
            // light gray, dark gray, or black brush each
            // time a WM_TIMER message is issued.

            hdc = GetDC(hwnd);
            GetClientRect(hwnd, &rc);
            if (i++ <= 4)
                FillRect(hdc, &rc, GetStockObject(i));
            else
                (i = 0);
            ReleaseDC(hwnd,hdc);
            break;

        case WM_DESTROY:

            // When the WM_DESTROY message is issued, the screen saver
            // must destroy any of the timers that were set at WM_CREATE
            // time.

            if (uTimer)
                KillTimer(hwnd, uTimer);
            break;
    }

    // DefScreenSaverProc processes any messages ignored by ScreenSaverProc.
    return DefScreenSaverProc(hwnd, message, wParam, lParam);
}

---

Code:

---

//resource.h
#include <windows.h>
#include <wingdi.h>
#include <scrnsave.h>
#ifndef ID_SPEED
#define ID_SPEED 200453
#endif
#ifndef ID_OK
#define ID_OK IDOK
#endif
#ifndef ID_CANCEL
#define ID_CANCEL IDCANCEL
#endif

---

Code:

---

//resource.rc
#include "resource.h"
DLG_SCRNSAVECONFIGURE DIALOG 6, 18, 160, 63
LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
STYLE DS_MODALFRAME | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
CAPTION "Sample Screen-Saver Setup"
FONT 8, "MS Shell Dlg"
BEGIN
    GROUPBOX      "Redraw Speed", 101, 0, 6, 98, 40
    SCROLLBAR    ID_SPEED, 5, 31, 89, 10
    LTEXT        "Fast", 103, 6, 21, 20, 8
    LTEXT        "Slow", 104, 75, 21, 20, 8
    PUSHBUTTON    "OK", ID_OK, 117, 10, 40, 14
    PUSHBUTTON    "Cancel", ID_CANCEL, 117, 32, 40, 14
END

LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
1                  RT_MANIFEST    "manifest.xml"

---

Code:

---

//manifest.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
  <dependency>
    <dependentAssembly>
      <assemblyIdentity type="win32" name="Microsoft.Windows.Common-Controls" version="6.0.0.0" processorArchitecture="*" publicKeyToken="6595b64144ccf1df" language="*"/>
    </dependentAssembly>
  </dependency>
  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
    <security>
      <requestedPrivileges>
        <requestedExecutionLevel
          level="asInvoker"
          uiAccess="false"/>
      </requestedPrivileges>
    </security>
  </trustInfo>
</assembly>

---

Hmmmm... it looks like it should work...

A couple of things to try...
1) Put a diagnostic Beep() in the switch so that you know the WM_HSCROLL it's being called correctly.
2) Test the return value of SetScrollPos() to be sure the function isn't failing.
3) Use a temporary static or edit control to visually report the value of lSpeed after setting the scroll pos.
4) Of course running it in debug mode will also be revealing.
5) You should also add SBS_HORZ style to your scrollbar's resource definitions... (control styles are important to getting correct behavior)