GfxBase DecideGfx(Symbol symbol)
{
var gfxs = symbol.Graphics;
if (gfxs.Count == 1)
return gfxs[0];
GfxBase gfx;
gfx = gfxs.OfType<VectorGfxBase>().FirstOrDefault();
if (gfx != null)
return gfx;
gfx = gfxs.OfType<BitmapGfx>().FirstOrDefault();
if (gfx != null)
return gfx;
throw new Exception();
}