向SourceView增加垂直行号标注

// 设置垂直行号标注
		CompositeRuler ruler = new CompositeRuler();
		LineNumberRulerColumn lineCol = new LineNumberRulerColumn();
		lineCol.setBackground(parent.getShell().getDisplay().getSystemColor(SWT.COLOR_GRAY));
		ruler.addDecorator(0, lineCol);
		sourceViewer = new SourceViewer(topComp, ruler, SWT.V_SCROLL | SWT.H_SCROLL );