C / C++ / MFC

void CDemoDialog::OnPaint()
{
   CPaintDC dc(this); // device context for painting
 
   // transfer the bitmap into paint DC using a transparent color  
   dc.TransparentBlt(
      10, 10, bmp.bmWidth, bmp.bmHeight, // destination coordinates and sizes
      &pDCTmp,                           // source DC .. your DC with bitmap
      0, 0, bmp.bmWidth, bmp.bmHeight,   // source coordinates and sizes
      RGB(255, 0, 0));                   // transparent color

}

int DialogFromTemplate (HWND parent, int DialogWth, int DialogHt, char* DlgTitle, DLGPROC handler)
{
   int nchar, ret;
   int x, y;
   RECT r;
   HGLOBAL hgbl;
   LPDLGTEMPLATE lpdt;
   LPWORD lpw;
   LPWSTR lpwsz;

   GetClientRect(parent, &r);	 	                                      // Get parent client area
   x =  ((r.right+r.left)/2);		                                     // Calc x client centre position
   y = ((r.bottom+r.top)/2);		                                     // Calc y client centre position

    /* from the client centre the dialog left is half width and top half height less */
    x -= DialogWth/2;
    y -= DialogHt/2;

   /* template size and position are in multiples of 2 .. yeah its weird */
    x /= 2;				                                       // X client left position in template units
    y /= 2;				                                       // Y client top position in template units
	
   hgbl = GlobalAlloc(GMEM_ZEROINIT, 1024);                               // Allocate memory
   if (!hgbl) return -1;		 	                                      // If allocate fail exit
   lpdt = (LPDLGTEMPLATE)GlobalLock(hgbl);                              // Lock the allocated memory
   lpdt->style = WS_POPUP | WS_CAPTION | WS_SYSMENU;  // Window style
   lpdt->cdit = 0;					  // Number of controls
   lpdt->x  = x;					  // X position
   lpdt->y  = y;					  // Y psoition
   lpdt->cx = DialogWth/2;				  // Window width (template units)
   lpdt->cy = DialogHt/2;				  // Window height (template units)
   lpw = (LPWORD)(lpdt + 1);				  // Set pointer address
   *lpw++ = 0;					  // No menu
   *lpw++ = 0;					  // Predefined dialog box class (by default)
   lpwsz = (LPWSTR)lpw;				  // Typecast pointer
   nchar = 1 + MultiByteToWideChar(CP_ACP, 0, DlgTitle, 
	  -1, lpwsz, 50);				  // Title of dialog
   lpw += nchar;					  // Increment by size of name
   *lpw++ = 0;					  // No creation data
   GlobalUnlock(hgbl);				  // Release lock on the memory block 
   ret = (int)DialogBoxIndirectParam(GetModuleHandle(0), 
     (LPDLGTEMPLATE)hgbl, parent, Handler,  0);		  // Create the dialog from template
   GlobalFree(hgbl);					  // Free the allocated memory
    return ret;				 	  // Return result
}