程序代码：

Private Declare Function SetClassLong Lib "user32" Alias "SetClassLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwnewlong As Long) As Long
Private Declare Function OleTranslateColor Lib "oleaut32.dll" (ByVal lOleColor As Long, ByVal lHPalette As Long, ByRef lColorRef As Long) As Long
Private Declare Function CreateSolidBrush Lib "gdi32.dll" (ByVal crColor As Long) As Long
Private Declare Function DeleteObject Lib "gdi32.dll" (ByVal hObject As Long) As Long
Private Declare Function CreatePatternBrush Lib "gdi32.dll" (ByVal hBitmap As Long) As Long
Private Declare Function InvalidateRect Lib "user32" (ByVal hwnd As Long, lpRect As Long, ByVal bErase As Long) As Long

Private Const GCL_HBRBACKGROUND As Long = -10

Private Function GDI_TranslateColor(OleClr As OLE_COLOR, Optional hPal As Integer = 0) As Long
    If OleTranslateColor(OleClr, hPal, GDI_TranslateColor) Then GDI_TranslateColor = &HFFFF&
End Function

Function GDI_CreateSoildBrush(bColor As OLE_COLOR) As Long
    GDI_CreateSoildBrush = CreateSolidBrush(GDI_TranslateColor(bColor))
End Function

Public Sub SetToolbarBG(hwnd As Long, hBmp As Long)
    DeleteObject SetClassLong(hwnd, GCL_HBRBACKGROUND, CreatePatternBrush(hBmp))
    InvalidateRect 0&, 0&, False
End Sub

Public Sub SetToolbarBK(hwnd As Long, hColor As OLE_COLOR)
    DeleteObject SetClassLong(hwnd, GCL_HBRBACKGROUND, GDI_CreateSoildBrush(hColor))
    InvalidateRect 0&, 0&, False
End Sub

Private Sub Command2_Click()
    Call SetToolbarBK(Toolbar1.hwnd, vbYellow)
End Sub

Private Sub Command1_Click()
    Call SetToolbarBK(Toolbar1.hwnd, vbBlue)
End Sub

Private Sub Form_Unload(Cancel As Integer)
    '这段代码一定要有哦，不然回不来就别找我耶
    SetToolbarBK Toolbar1.hwnd, vbButtonFace
End Sub