int firstLine; int lastLine;
public void redrawRange(int start, int length, boolean clearBackground) {	checkWidget();	int end = start + length;	int contentLength = content.getCharCount();	int firstLine;	int lastLine;		if (start > end || start < 0 || end > contentLength) {		SWT.error(SWT.ERROR_INVALID_RANGE);	}		firstLine = content.getLineAtOffset(start);	lastLine = content.getLineAtOffset(end);	// reset all affected lines but let the redraw recalculate only 	// those that are visible.	lineCache.reset(firstLine, lastLine - firstLine + 1, true);	internalRedrawRange(start, length, clearBackground);}