caretOffset = getBidiOffsetAtMouseLocation(caretX, caretLine);
caretOffset = getBidiOffsetAtMouseLocation(columnX, caretLine);
void doLineUp() {	if (caretLine > 0) {		caretLine--;		if (isBidi()) {			caretOffset = getBidiOffsetAtMouseLocation(caretX, caretLine);		}		else {			caretOffset = getOffsetAtMouseLocation(caretX, caretLine);		}			}}