protected void ReadGraphicControlExt()
{
inp.ReadByte(); // block size
int packed = inp.ReadByte(); // packed fields
dispose = (packed & 0x1c) >> 2; // disposal method
if (dispose == 0)
dispose = 1; // elect to keep old image if discretionary
transparency = (packed & 1) != 0;
delay = ReadShort() * 10; // delay inp milliseconds
transIndex = inp.ReadByte(); // transparent color index
inp.ReadByte(); // block terminator
}