fragment 内部异步更新UI,该如何解决

fragment 内部异步更新UI
我想在fragment中用不断地更换topmargin来做一个可挤压的抽屉，但在Fragment中用runable结合hander报ui线程错误

public class fragment_mylight extends Fragment {
	 private Handler handler=null;  
	private LinearLayout drawer;
	private final int MARGIN_HEIGHT_ONCE=20;
	private int marginHeight;
	private int drawerHeight;
	private boolean flag;
	@Override
	 public View onCreateView(LayoutInflater inflater, ViewGroup container,  
	            Bundle savedInstanceState) {
		  handler=new Handler();  
		View view =inflater.inflate(com.ks.uidemo.R.layout.fragment_mylight, container,false);
		 drawer=(LinearLayout)view.findViewById(R.id.dropdown_drawer);
		RelativeLayout content =(RelativeLayout)view.findViewById(R.id.drawer_content);
		final ImageButton handerButton=(ImageButton)view.findViewById(R.id.drawer_hander);
		ViewTreeObserver vob =handerButton.getViewTreeObserver();
		 LinearLayout.LayoutParams lp =new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,drawerHeight);
		// lp.topMargin=-150;
		// drawer.setLayoutParams(lp);
		  final Handler mHandler = new Handler(){ 
			 @Override  
			public void handleMessage(Message msg) {
				 LinearLayout.LayoutParams ll=(LinearLayout.LayoutParams)msg.obj;
				 drawer.setLayoutParams(ll);
				 super.handleMessage(msg);
			 }

		};
		vob.addOnPreDrawListener(new OnPreDrawListener(){

			@Override
			public boolean onPreDraw() {
				 drawerHeight=drawer.getLayoutParams().height;
				int width=handerButton.getMeasuredHeight();
				 marginHeight=drawerHeight-width;
				 LinearLayout.LayoutParams lp =new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,drawerHeight);
					lp.topMargin=-marginHeight;
					//drawer.setLayoutParams(lp);
				return true;
			}
			
		});
		final Runnable runable=new Runnable(){
			@Override
			public void run() {
				int timer;
				if(marginHeight%MARGIN_HEIGHT_ONCE==0)timer=marginHeight/MARGIN_HEIGHT_ONCE;
				else timer=marginHeight/MARGIN_HEIGHT_ONCE+1;
				int margin=flag?MARGIN_HEIGHT_ONCE:-MARGIN_HEIGHT_ONCE;
				for(int i=0;i<timer;i++){
					LinearLayout.LayoutParams lp1 =new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,drawerHeight);
					if(margin>0){
						lp1.topMargin=Math.max(lp1.bottomMargin+margin,0);
					}
					else{
						lp1.topMargin=Math.min(lp1.bottomMargin+margin,-marginHeight);
					}

					try {
						Thread.sleep(20);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					mHandler.obtainMessage(1, lp1).sendToTarget();
				}
			}
			
		};
		handerButton.setOnClickListener(new OnClickListener(){
			@Override
			public void onClick(View arg0) {
				flag=flag==true?false:true;
    new Thread(runable).start();//在这里报 only the original thread that created a view hierarchy can touch its view			
}
			
		});
	    return view; 
	}
	

------解决思路----------------------
对topmargin的处理，直接放handler里吧，发消息出去就行了
------解决思路----------------------
直接在handler里面操作呀！