protected virtual bool PreProcessWmKeyDown_PageUp(ref Message m)
{
long pos = _hexBox._bytePos;
int cp = _hexBox._byteCharacterPos;
if (pos == 0 && cp == 0)
return true;
pos = Math.Max(0, pos - _hexBox._iHexMaxBytes);
if (pos == 0)
return true;
_hexBox.SetPosition(pos);
if (pos < _hexBox._startByte)
{
_hexBox.PerformScrollPageUp();
}
_hexBox.ReleaseSelection();
_hexBox.UpdateCaret();
_hexBox.Invalidate();
return true;
}