UAC shield icon on Windows 7 is different from those on Vista. Those on 7 is colored with blue and yellow. Those on Vista is with the four colors (red, green, blue and yellow.) But any document associate with this fact is not found.

So I think following program have version incompatibility:

  1. using the icon which is in your program's resource
  2. using SystemIcons.Shield (.NET Framework)

Why SystemIcons.Shield has incompatibility? SystemIcons.Shield yields an four-colors shield icon even if the program is running on windows 7. So, I think SystemIcons.Shield shall not be used for UAC.

Using SHGetStockIconInfo() with SIID_SHIELD seems to be a correct answer. This code return the UAC shield icon colored with blue and yellow on windows 7, and colored with four colors on Vista. Example code is as follows:

sii.cbSize = sizeof(SHSTOCKICONINFO);
SHGetStockIconInfo(SIID_SHIELD, SHGSI_ICON, &sii);
sii.hIcon; // this is a UAC shield icon handler!

If your program is a .NET Framework application, P/Invoke is required such as following code. Another example code is also available at CodeProject.

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
    public Int32 cbSize;
    public IntPtr hIcon;
    public Int32 iSysImageIndex;
    public Int32 iIcon;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=260)]
    public string szPath;

[DllImport("shell32.dll", CharSet=CharSet.Unicode, SetLastError=true)]
static extern void SHGetStockIconInfo(UInt32 siid, UInt32 uFlags,
                                      ref SHSTOCKICONINFO sii);

Note that SIID_SHIELD shall be used for UAC prompts only, which is written at SIID_SHIELD description at MSDN.

See also