BMAP* createTransBMP(int SizeX, SizeY, int CDepth)
{

   STRING* bmpCreateString = str_create("");
   str_cat_num(bmpCreateString, "#%.0fx", SizeX);
   str_cat_num(bmpCreateString, "%.0fx",  SizeY);
   str_cat_num(bmpCreateString, "%.0f",   CDepth ); //Should be 32 for your purpose
   BMAP* bBlack = bmap_create(bmpCreateString);
   //Alright! Bmap is created... though we need it transparent!
   long i;
   //Every fourth byte is the alpha channel of the pixel!
   for(i = 3; i<= SizeX*SizeY*CDepth; i+=4)
      (bBlack->pixels)[i] = (byte)127; //set it to half opaque
   return bBlack;
}

function main()
{
   PANEL* myTransBlackPanel = pan_create("flags = SHOW", 1);
   myTransBlackPanel->bmap = createTransBMP(screen_size.x, screen_size.y, (int)32);
   myTransBlackPanel->size_x = myTransBlackPanel->bmap->width;
   myTransBlackPanel->size_y = myTransBlackPanel->bmap->height;
}