Hi, how is the "better" way tom open a new/public screen and its background being black?

Now I'm using:

IIntuition->OpenScreenTags(NULL,
...
is_fullscreen? SA_BackFill : TAG_IGNORE , backfillhook,
...
TAG_END);

and the hook:

...
IGraphics->RectFillColor(&newrp,
   msg->Bounds.MinX, msg->Bounds.MinY,
   msg->Bounds.MaxX, msg->Bounds.MaxY,
   0xff000000); // black color
...

I tried (IIRC) SA_Colors, (and set background Pen0 to black) but as it changes pen colors then all window/gagdets I open there have black background too (messages/texts can't be read)