Eclipse Graphical Editor does not display a xml source code - error bug

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}

		@Override
		protected void onDraw(Canvas canvas) {

			canvas.drawColor(Color.CYAN);
			Paint p = new Paint();
			// smooths
			p.setAntiAlias(true);
			p.setColor(Color.RED);
			p.setStyle(Paint.Style.STROKE); 
			p.setStrokeWidth(4.5f);
			// opacity
			//p.setAlpha(0x80); //
//drawRect (float left, float top, float right, float bottom, Paint paint) 
			canvas.drawRect(10, 10, 30, 30, p);
		}

	}
}

AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure you want to exit application?")
       .setCancelable(false)
       .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
                MyActivity.this.finish(); //Close  this Activity for example: MyActivity.java
           }
       })
       .setNegativeButton("No", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
                // some code if you want
                dialog.cancel();
           }
       });
AlertDialog alert = builder.create();
alert.show();

WebView_webview = (WebView)findViewById(R.id.webViewMapa);
_webview.getSettings().setBuiltInZoomControls(true);
_webview.setBackgroundColor(Color.parseColor("#E8EAE8"));
// _webview.loadUrl( ... some your page

Bitmap b = Bitmap.createBitmap(_webview.getWidth()/2, _webview.getHeight(), Bitmap.Config.ARGB_8888);
// you can to draw on bitmap
Canvas c = new Canvas(b);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStrokeWidth(15.f);
paint.setColor(Color.RED);
paint.setStyle(Paint.Style.STROKE);
//paint.setShadowLayer(5.f, 0, 5.f, 0xFF000000);
_webview.draw(c); // put into canvas content of view like image
c.drawLine(70, 0, 150, 350, paint);// draw some line
//Rect oval = new Rect(0, 0, 100, 100);
//c.drawArc(oval, 0, 180, false, paint);

// you can show bitmap in other view
((ImageView)findViewById(R.id.imageView1)).setImageBitmap(b);

public class Vypocet extends Activity {
 Spinner   hSpinnerMetry;
// .......
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

	       hSpinnerMetry = (Spinner) findViewById(R.id.idSpinnerMetry);
	        ArrayAdapter<CharSequence> adapterMetry = ArrayAdapter.createFromResource(
	        		this, R.array.metry_array, android.R.layout.simple_spinner_item);
	        adapterMetry.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
	        hSpinnerMetry.setAdapter(adapterMetry);
			
	           hSpinnerMetry.setOnItemSelectedListener(
	                    new OnItemSelectedListener() {
	                        public void onItemSelected(
	                                AdapterView<?> parent, View view, int position, long id) {
	                        int nPos = position;
	                        }

	                        public void onNothingSelected(AdapterView<?> parent) {
	                        
	                        }
	                    });	        

      }
}

<string-array name="metry_array">
<item>m</item>
<item>dm</item>
<item>cm</item>
<item>mm</item>
</string-array>