visibleItemCount = Math.max (visibleItemCount, 1);
public void showItem (TableItem item) {	checkWidget ();	if (item == null) error (SWT.ERROR_NULL_ARGUMENT);	if (item.isDisposed ()) error (SWT.ERROR_INVALID_ARGUMENT);	if (item.parent != this) return;		int index = item.index;	int visibleItemCount = (getClientArea ().height - getHeaderHeight ()) / itemHeight;	/* nothing to do if item is already in viewport */	if (topIndex <= index && index < topIndex + visibleItemCount) return;		if (index <= topIndex) {		/* item is above current viewport, so show on top */		setTopIndex (item.index);	} else {		/* item is below current viewport, so show on bottom */		setTopIndex (Math.min (index - visibleItemCount + 1, itemsCount - 1));	}}