Strange effect on scrollbars

[Niara]

Hello, I have been trying to use scrollbars on my app, but I have seen that there's a strange effect depending the size of the scrollbar. That is the sample:

#include <windows.h>
#define BSX 1000

LRESULT CALLBACK procedimentPrincipal (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
SCROLLINFO si;
HINSTANCE hInstance=(HINSTANCE)GetWindowLong(hwnd,GWL_HINSTANCE);
switch (msg)
    {
    case WM_CREATE:
        {
        CreateWindowEx(0,"SCROLLBAR","",WS_CHILD|WS_VISIBLE|SBS_HORZ,10,10,200,50,hwnd,(HMENU)BSX,hInstance,NULL);
        memset(&si,0,sizeof(si));
        si.cbSize=sizeof(SCROLLINFO);
        si.fMask=SIF_POS|SIF_RANGE|SIF_PAGE;
        si.nMin=0;
        si.nMax=100;
        si.nPage=0;
        si.nPos=50;
        si.nTrackPos=50;
        SetScrollInfo(GetDlgItem(hwnd,BSX),SB_HORZ,&si,TRUE);
        }
    break;
    case WM_LBUTTONDOWN:
        {
        memset(&si,0,sizeof(si));
        si.cbSize=sizeof(SCROLLINFO);
        si.fMask=SIF_POS;
        si.nPos=80;
        si.nTrackPos=80;
        SetScrollInfo(GetDlgItem(hwnd,BSX),SB_HORZ,&si,TRUE);
        }
    break;
	case WM_DESTROY: {PostQuitMessage(0);} break;
    default: return DefWindowProc (hwnd, msg, wParam, lParam);
    }
return 0;
}

int WINAPI WinMain (HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpszArgument,int ncs)
{
HWND hwnd;
MSG msg;
WNDCLASSEX wc;

wc.hInstance = hInstance;
wc.lpszClassName = "exbarrascroll";
wc.lpfnWndProc = procedimentPrincipal;
wc.style = CS_DBLCLKS;
wc.cbSize = sizeof (WNDCLASSEX);
wc.hIcon = LoadIcon(hInstance,"icona");
wc.hIconSm = LoadIcon(hInstance,"icona");
wc.hCursor = LoadCursor (NULL,IDC_ARROW);
wc.lpszMenuName = NULL;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hbrBackground = CreateSolidBrush(RGB(255,255,255));

if(!RegisterClassEx(&wc)) return 0;
hwnd=CreateWindowEx(0,"exbarrascroll","",WS_OVERLAPPEDWINDOW,0,0,640,480,HWND_DESKTOP,NULL,hInstance,NULL);

ShowWindow(hwnd,SW_SHOWDEFAULT);
UpdateWindow(hwnd);

while(TRUE==GetMessage(&msg,NULL,0,0))
    {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
    }
return msg.wParam;
}

I'm using DevCpp with the default MingW compiler. The result is a strange scrollbar, with 2 sets of scrollbars (2 sets of arrows, thumbs, etc), one bigger than the other.
but there's another strange effect, if I create the scrollbar width only 15px high, the second scroll set is not drawed but I cannot set the track position.

How should I solve that?

Thank's in advance
Niara

[Niara]

Ok, the problem is partialy solved: I have created my own scrollbar window class, it's not fully working but for the moment is a good aproach.

Niara