How to use stock-objects with GDI+

I was using the following pattern to record an enhanced meta-file for a later playback:

POINT pts[] = {
//.....
};

::SelectObject(hEnhDC, ::GetStockObject(LTGRAY_BRUSH));
::Polygon(hEnhDC, pts, _countof(pts));

Now I'm forced to use GDI+ to provide anti-aliasing, so I'm trying to convert that code sample:

Gdiplus::Point pts[] = {
//...
};

Gdiplus::Graphics grx(hEnhDC);
Gdiplus::Pen pen(Gdiplus::Color(255, GetRValue(clrPen), GetGValue(clrPen), GetBValue(clrPen)), PEN_THICKNESS);

grx.FillPolygon(&brush, pts, _countof(pts));
grx.DrawPolygon(&pen, pts, _countof(pts));

The issue is how do I convert a stock-object HBRUSH from ::GetStockObject(LTGRAY_BRUSH) to GDI+ Brush object?

EDIT: Guys, thank you for all your suggestions. And I apologize for not providing more details. This question is not about getting the RGB color triplet from the stock brush. I can do all that with the GetSysColor function, or with the LOGBRUSH like you showed below.

The trick lies in the first sentence above. I am recording an enhanced metafile that may be played on a separate computer, so I cannot hard-code colors into it.

Let me explain. Say, the first GDI example (let's simplify it down to a triangle with a gray fill):

POINT pts[] = {
    {100, 100,},
    {100, 120,},
    {120, 100,},
};

::SelectObject(hEnhDC, ::GetStockObject(LTGRAY_BRUSH));
::Polygon(hEnhDC, pts, _countof(pts));

If I then call GetEnhMetaFileBits on that meta-file, I'll get the following data:

So as you see the EMR_SELECTOBJECT object in that recorded meta-file specifies the LTGRAY_BRUSH = 0x80000001, which will be properly substituted for the color when that meta-file is played on the target system.

And that's what I'm trying to achieve here with GDI+. For some reason it only seems to support hard-coded color triplets in its Brush class. That's why I asked.

Otherwise, one solution is to parse the enhanced meta-file's raw data. (For GDI+ it is a much more complex structure though, that also involves parsing EMR_GDICOMMENT objects.) And then substitute the needed color on the target system before the GDI+ meta-file is played. But it involves writing a lot of code, which I was trying to avoid at this stage ...

I’m afraid you can’t easily convert.

A simple workaround is create GDI+ solid brush with the same color.

See this spec for color values of GDI stock objects, that particular brush has color #C0C0C0