BOOL create_addressBar(HWND hwnd, HINSTANCE hInstance, LPCTSTR string)
{
HWND hwndCB, hwndTB=NULL, hwndRB;
REBARINFO rbi;
RECT rc;
REBARBANDINFO rbBand;
long dwBtnSize=0;
INITCOMMONCONTROLSEX icex;

icex.dwSize = sizeof(INITCOMMONCONTROLSEX);
icex.dwICC = ICC_BAR_CLASSES;
InitCommonControlsEx(&icex);
if (!(hwndRB=CreateWindowEx(WS_EX_TOOLWINDOW, REBARCLASSNAME, NULL,
WS_CHILD|WS_VISIBLE|WS_CLIPSIBLINGS|
WS_CLIPCHILDREN|RBS_VARHEIGHT|CCS_NODIVIDER|RBS_REGISTERDROP,
2 + 70 + 10, 2, // X, Y position
70, 34, // Width, Height
hwnd,
(HMENU)2001, hInstance, 0)))
{
tbx_geterror();
MessageBox(hwnd, "Can't create browser child window!", "ERROR", MB_OK);
return FALSE;
}

// Initialize and send the REBARINFO structure.
rbi.cbSize = sizeof(REBARINFO); // Required when using this
// structure.
rbi.fMask = 0;
rbi.himl = (HIMAGELIST)NULL;
SendMessage(hwndRB, RB_SETBARINFO, 0, (LPARAM)&rbi);
// Initialize structure members that both bands will share.
rbBand.cbSize = sizeof(REBARBANDINFO); // Required
rbBand.fMask = RBBIM_COLORS | RBBIM_TEXT | RBBIM_BACKGROUND |
RBBIM_STYLE | RBBIM_CHILD | RBBIM_CHILDSIZE |
RBBIM_SIZE;
rbBand.fStyle = RBBS_CHILDEDGE | RBBS_FIXEDBMP;
rbBand.hbmBack = LoadBitmap(hInstance,MAKEINTRESOURCE(700));
// Create the combo box control to be added.

hwndCB = CreateWindowEx(WS_EX_TOOLWINDOW, "ComboBox", NULL,
WS_CHILD|WS_VISIBLE|WS_CLIPSIBLINGS|WS_CLIPCHILDREN,
2, 2, // X, Y position
10, 20, // Width, Height
hwnd,
(HMENU)2002, hInstance, 0);
SendMessage( hwndCB, CB_ADDSTRING, 0, (LPARAM) (LPCTSTR) string );
SetWindowText(hwndCB, string);
// Set values unique to the band with the combo box.
GetWindowRect(hwndCB, &rc);
rbBand.lpText = "Address";
rbBand.hwndChild = hwndCB;
rbBand.cxMinChild = 0;
rbBand.cyMinChild = rc.bottom - rc.top;
rbBand.cx = 200;

SendMessage(hwndRB, RB_INSERTBAND, (WPARAM)-1, (LPARAM)&rbBand);

CreateMyFont();
if (FontHandle) DeleteObject(FontHandle);

return TRUE;
}

Versuchs mal mit CBS_DROPDOWN oder liege ich da falsch.