Ok - I'm getting somewhere:) I've managed to set a toolbar direct - but it causes "oddness"... 
 
As a base I'm going to try and get the rebar example in the page below working:
 
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/shellcc/platform/commctls/rebar/rebar.asp
 
The C code (below) to create this toolbar is straightforward - and from my (basic) understanding there should be no difficulty reproducing this example in Win32::GUI.
HWND WINAPI CreateRebar(HWND hwndOwner)
{
   REBARINFO     rbi;
   REBARBANDINFO rbBand;
   RECT          rc;
   HWND   hwndCB, hwndTB, hwndRB;
   DWORD  dwBtnSize;
   INITCOMMONCONTROLSEX icex;
   
   icex.dwSize = sizeof(INITCOMMONCONTROLSEX);
   icex.dwICC   = ICC_COOL_CLASSES|ICC_BAR_CLASSES;
   InitCommonControlsEx(&icex);
   hwndRB = CreateWindowEx(WS_EX_TOOLWINDOW,
                           REBARCLASSNAME,
                           NULL,
                           WS_CHILD|WS_VISIBLE|WS_CLIPSIBLINGS|
                           WS_CLIPCHILDREN|RBS_VARHEIGHT|
                           CCS_NODIVIDER,
                           0,0,0,0,
                           hwndOwner,
                           NULL,
                           g_hinst,
                           NULL);
   if(!hwndRB)
      return NULL;
   // Initialize and send the REBARINFO structure.
   rbi.cbSize = sizeof(REBARINFO);  // Required when using this
                                    // structure.
   rbi.fMask  = 0;
   rbi.himl   = (HIMAGELIST)NULL;
   if(!SendMessage(hwndRB, RB_SETBARINFO, 0, (LPARAM)&rbi))
      return NULL;
   // 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(g_hinst,
                              MAKEINTRESOURCE(IDB_BACKGRND));   
   // Create the combo box control to be added.
   hwndCB = CreateComboBox(hwndRB);
   // Set values unique to the band with the combo box.
   GetWindowRect(hwndCB, &rc);
   rbBand.lpText     = "Combo Box";
   rbBand.hwndChild  = hwndCB;
   rbBand.cxMinChild = 0;
   rbBand.cyMinChild = rc.bottom - rc.top;
   rbBand.cx         = 200;
   
   // Add the band that has the combo box.
   SendMessage(hwndRB, RB_INSERTBAND, (WPARAM)-1, (LPARAM)&rbBand);
   
   // Create the toolbar control to be added.
   hwndTB = CreateToolbar(hwndOwner, dwStyle);
   
   // Get the height of the toolbar.
   dwBtnSize = SendMessage(hwndTB, TB_GETBUTTONSIZE, 0,0);

   // Set values unique to the band with the toolbar.
   rbBand.lpText     = "Tool Bar";
   rbBand.hwndChild  = hwndTB;
   rbBand.cxMinChild = 0;
   rbBand.cyMinChild = HIWORD(dwBtnSize);
   rbBand.cx         = 250;

   // Add the band that has the toolbar.
   SendMessage(hwndRB, RB_INSERTBAND, (WPARAM)-1, (LPARAM)&rbBand);
   return (hwndRB);
}
----- Original Message -----
From: Stephen Pick
To: Win32-GUI
Sent: Thursday, February 19, 2004 12:45 PM
Subject: RE: [perl-win32-gui-users] Rebar and toolbar revisited

Hi,
 
Can you not set the parent to be the handle of the rebar section that you're adding the toolbar into? I know not much about rebars but I do know that they have HWNDs that would satisfy a toolbars need to have a parent window.
 
Steve