256 color bitmap buttons in Outlook

[Diego]

Hi all,

I am working on an Outlook add-in which adds a couple of buttons to the
toolbar. These buttons have a 16 color bitmap displayed. The purple color
in the bitmaps is the transparent color when Outlook runs.

I want to change the button bitmaps to be 256 color. When I do this I
cannot get transparency to work like it does with the 16 colot bitmaps.
The purple shows up. Is there anyway I can get a color to be transparent?

Below is the code used to add the button to the toolbar. I am using
Outlook XP, but have the same thing happen with Outlook 2003.

Any help would be greatly appreciated.

Regards,
Diego

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TBADDBITMAP tbab;
tbab.hInst = AfxGetInstanceHandle();
tbab.nID = uiBitmapID;
*puiToolBarM = SendMessage(hwndToolbar,
TB_ADDBITMAP, 1, (LPARAM)&tbab);