Eclipse ADT plugin not recent graphical layout editor

ListFragment show only one item issue

Try to change layout_width to 0dp

   <fragment android:name="cz.okhelp.android.fragchangfromlist.ArticleFragment"
              android:id="@+id/article_fragment"
              android:layout_weight="2"
              android:layout_width="0dp"
              android:layout_height="match_parent" />
<!--todo LAYOUT_WIDTH have to be 0dp !!!!!!!!!!!!!!!!!!!!! -->

    <FrameLayout android:id="@+id/article_fragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="2" />

WakeLock, PowerManager,uses-permission Android sample.
Main.java

public class Main extends Activity {
	    private SensorManager mSensorManager;
	    private PowerManager mPowerManager;
	    private WindowManager mWindowManager;
	    private WakeLock mWakeLock;
	    private Button button;
	    private TextView textView;

	    /** Called when the activity is first created. */
	    @Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
try{
	        // Get an instance of the SensorManager
	        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

	        // Get an instance of the PowerManager
	        mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);

	        // Get an instance of the WindowManager
	        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
	        mWindowManager.getDefaultDisplay();

	        // Create a bright wake lock
	        mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass()
	                .getName());

	        setContentView(R.layout.main);
	        textView = (TextView)findViewById(R.id.textView1);
	        button = (Button)findViewById(R.id.button1);
	        button.setOnClickListener(mButtonStopListener);
	       
	        
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			Log.e("onCreate", e.getMessage());
		}
} // END onCreate
	    
	    View.OnClickListener mButtonStopListener = new OnClickListener() {
	    	public void onClick(View v) {
		        try {
					mWakeLock.release();
					textView.setText("mWakeLock.release()");
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
					Log.e("onPause",e.getMessage());
				}
	    	
	    	}
	    };

	    @Override
	    protected void onResume() {
	        super.onResume();
	        /*
	         * when the activity is resumed, we acquire a wake-lock so that the
	         * screen stays on, since the user will likely not be fiddling with the
	         * screen or buttons.
	         */
	        
	        try {
				mWakeLock.acquire();
				textView.setText("mWakeLock.acquire()");
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onResume", e.getMessage());
			}

	    }

	    @Override
	    protected void onPause() {
	        super.onPause();

	        // and release our wake-lock
	        try {
				mWakeLock.release();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onPause",e.getMessage());
			}
	    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="//schemas.android.com/apk/res/android"
      package="cz.okhelp.Main"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.HARDWARE_TEST"></uses-permission>
<uses-permission android:name="android.permission.VIBRATE"></uses-permission>

<uses-permission android:name="android.permission.WAKE_LOCK"></uses-permission>

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ScreenBrightnessActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

Try add to AndroidManifest.xml configChanges for your Activity
android:configChanges="keyboardHidden|orientation|screenSize"

 <activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:configChanges="keyboardHidden|orientation|screenSize"
                  >

Get display, screen resolution - dimension Android phone development example source code.

 Display display = getWindowManager().getDefaultDisplay();
int nWidth = display.getWidth();
int nHeight = display.getHeight();

          DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            //get density per inch for example: 120 , 160 , 240
            mXDpi = metrics.xdpi; // 160 The exact physical pixels per inch of the screen in the X dimension. 
            mYDpi = metrics.ydpi;

// density
int nDensity = metrics.densityDpi; // 160 screen density expressed as dots-per-inch

          float  mMetersToPixelsX = mXDpi / 0.0254f; // 1 inch == 0.0254 metre
          float  mMetersToPixelsY = mYDpi / 0.0254f;
          
// Resolution
// The total number of physical pixels on a screen.
int wPix = metrics.widthPixels; // 320 The absolute width of the display in pixels.
int hPix = metrics.heightPixels; // 480 The absolute height of the display in pixels.
int nWidthDisplay = (wPix < hPix)? wPix : hPix;

float nWidthScreenInInch = wPix / mXDpi; //320 / 160 == 2.0 in inch.
float nHeightScreenInInch = hPix / mYDpi; //480 / 160 == 3.0 in inch.

// for example:
// density 120 per inch
//width 320 pix / 120 dpi == width 2.66 inch
//height 480 pix / 120 dpi == height 4.0 inch 

// density 240 per inch
//width 320 pix / 240 dpi == width 1.33 inch
//height 480 pix / 240 dpi == height 2.0 inch 

Example:
HTC Desire HD
11 (4.3) Diagonal cm (in)
480×800 Resolution
85 (217) ppcm (PPI - Pixels per inch)

480 / 217 = 2.21 inch
800 / 217 = 3.69 inch
Math.sqrt( 2.21*2.21 + 3.69 * 3.69) = 4.3 inch - diagonal

//en.wikipedia.org/wiki/Pixels_per_inch
//en.wikipedia.org/wiki/Dots_per_inch

Typical screen widths:

320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).


Emulator skins in the Android SDK
//developer.android.com/guide/practices/screens_support.html

	Low density (120), ldpi	Medium density (160), mdpi	High density (240), hdpi	Extra high density (320), xhdpi
Small screen	QVGA (240x320)		480x640
Normal screen	WQVGA400 (240x400) WQVGA432 (240x432)	HVGA (320x480)	WVGA800 (480x800) WVGA854 (480x854) 600x1024	640x960
Large screen	WVGA800** (480x800) WVGA854** (480x854)	WVGA800* (480x800) WVGA854* (480x854) 600x1024
Extra Large screen	1024x600	WXGA (1280x800)† 1024x768 1280x768	1536x1152 1920x1152 1920x1200	2048x1536 2560x1536 2560x1600
* To emulate this configuration, specify a custom density of 160 when creating an AVD that uses a WVGA800 or WVGA854 skin. ** To emulate this configuration, specify a custom density of 120 when creating an AVD that uses a WVGA800 or WVGA854 skin. † This skin is available with the Android 3.0 platform

File->Settings->Plugins and disable some plugins:

• Google Cloud Testing


• Google Cloud Tools Core


• Google Cloud Tools for Android Studio


• CVS Integration


• Git Integration


• GitHub


• hg4idea


• Subversion Integration

Use Emulator AVD with small memmory usage. For example: Virtual tablet with hight resolution have big memmory usage. Virtual phone with 240x320 resolution have small memmory usage.

Use instaed of Emulator, real device connected by USB (smarphone Samsung Galaxy or other recommended by Google whit debugable mode).

If you notice that Android Studio works slowly, consider the possibility to reduce the number of folders under antivirus protection.
Each antivirus check in your project consumes resources. You can significantly improve the performance, if you exclude certain folders from the antivirus protection.