How to change the background color of a windows context menu using the winapi

Question

I am currently trying to customize a context menu in Outlook. For the regulars I have had a series of issues which can be seen in this question and with this question.

I would like to adjust the background color a little.

        Dim hBrush As IntPtr = NativeMethodsEX.CreateSolidBrush(ColorTranslator.ToWin32(System.Drawing.Color.Red))                
        Dim mi As New NativeMethodsEX.MenuInfo

            With mi
                .cbSize = Marshal.SizeOf(mi)
                .fMask = NativeMethodsEX.MIM_STYLE Or NativeMethodsEX.MIM_BACKGROUND Or NativeMethodsEX.MIM_APPLYTOSUBMENUS
                .dwStyle = NativeMethodsEX.MNS_NOCHECK
                .hbrBack = hBrush
            End With

            NativeMethodsEX.SetMenuInfo(aHwnd, mi)

This code however produces this;.

How can I also change the background of the left hand side or what even is the class name of that part of the window. Also it has a border as well. What is its class name or how can I either remove it or change it?