Cleanup GLContext special entries: getOffscreenContextPixelDataType(), getOffscreenContextReadBuffer(), .. ; Add GLFBODrawable API entries for multi buffering (no impl. yet); GLJPanel 1st simplification using offscreen drawable

- Cleanup GLContext special entries: getOffscreenContextPixelDataType(), getOffscreenContextReadBuffer(), .. ;
  - add: getDefaultReadBuffer() (-> exposed via GLBase as well)
  - add: isGLOrientationFlippedVertical()
  - add: getDefaultPixelDataType()
  - removed impl: getOffscreenContextPixelDataType()
  - removed impl: getOffscreenContextReadBuffer()
  - removed impl: offscreenImageNeedsVerticalFlip()

- Add GLFBODrawable API entries for multi buffering (no impl. yet);
  - TODO: Add implementation code in GLFBODrawableImpl

- GLJPanel 1st simplification using FBO
  - Use above new GL/GLContext entries
  - Fix: getNativeSurface() and getHandle()
  - TODO:
    - Remove distinction of 'pbuffer' and 'software',
    - Use GLDrawableFactory.createOffscreenDrawable(..)
    - Use GL for FBO swapping

19 files changed, 187 insertions, 120 deletions

diff --git a/make/config/jogl/gl-impl-CustomJavaCode-common.java b/make/config/jogl/gl-impl-CustomJavaCode-common.java
index 283a4e623..8e8165fff 100644
--- a/make/config/jogl/gl-impl-CustomJavaCode-common.java
+++ b/make/config/jogl/gl-impl-CustomJavaCode-common.java
@@ -113,3 +113,8 @@
       return _context.getDefaultReadFramebuffer();
     }
 
+    @Override
+    public final int getDefaultReadBuffer() {
+      return _context.getDefaultReadBuffer();
+    }
+
diff --git a/make/scripts/tests-x64.bat b/make/scripts/tests-x64.bat
index db7e27264..719435d74 100755
--- a/make/scripts/tests-x64.bat
+++ b/make/scripts/tests-x64.bat
@@ -6,9 +6,6 @@ REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestShutdownC
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestShutdownCompleteAWT %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.acore.TestMainVersionGLWindowNEWT %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.offscreen.TestOffscreen01GLPBufferNEWT -time 5000
-REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWT01GLn
-REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestBug551AWT %*
-REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.awt.TestSwingAWT01GLn
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestSharedContextListAWT -time 5000
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestSharedContextListNEWT -time 5000
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestSharedContextListNEWT2 %*
@@ -16,8 +13,16 @@ REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.acore.TestSharedCon
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.acore.TestGLProfile01NEWT %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.acore.TestGLProfile02NEWT %*
 REM scripts\java-win64-dbg.bat  com.jogamp.opengl.test.junit.jogl.acore.TestGLContextDrawableSwitchNEWT %*
+
+REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.awt.TestSwingAWT01GLn
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestGLCanvasAWTActionDeadlock00AWT %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestGLCanvasAWTActionDeadlock02AWT %*
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWT01GLn
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestBug551AWT %*
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWT03GLCanvasRecreate01
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWTCardLayoutAnimatorStartStopBug532 %*
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestJScrollPaneMixHwLw01AWT %*
+scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestBug642JSplitPaneMixHwLw01AWT %*
 
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.newt.TestGearsNewtAWTWrapper %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.newt.TestGearsNEWT -time 30000
@@ -25,10 +30,8 @@ REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.es1.newt.
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT %*
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT -vsync -time 4000 -x 10 -y 10 -width 100 -height 100 -screen 0
 REM scripts\java-win64.bat com.jogamp.opengl.test.junit.jogl.demos.es2.newt.TestGearsES2NEWT -vsync -time 40000 -width 100 -height 100 -screen 0 %*
-REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWTCardLayoutAnimatorStartStopBug532 %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsAWT -time 5000
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsGLJPanelAWT -time 5000
-REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.awt.TestAWT03GLCanvasRecreate01
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.newt.TestSwingAWTRobotUsageBeforeJOGLInitBug411
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.glsl.TestTransformFeedbackVaryingsBug407NEWT
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.glsl.TestGLSLSimple01NEWT -time 2000
@@ -54,7 +57,7 @@ REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.newt.parenting.TestP
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.newt.parenting.TestParenting04SWT %*
 
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestSWTAccessor03AWTGLn %*
-scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestSWTJOGLGLCanvas01GLn %*
+REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestSWTJOGLGLCanvas01GLn %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestNewtCanvasSWTGLn %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestNewtCanvasSWTBug628ResizeDeadlock %*
 REM scripts\java-win64-dbg.bat com.jogamp.opengl.test.junit.jogl.swt.TestSWTBug643AsyncExec %*
diff --git a/make/scripts/tests.sh b/make/scripts/tests.sh
index 628ab706b..42358067a 100755
--- a/make/scripts/tests.sh
+++ b/make/scripts/tests.sh
@@ -113,7 +113,7 @@ function jrun() {
     #D_ARGS="-Djogl.debug.GLContext -Djogl.debug.GLProfile"
     #D_ARGS="-Djogl.debug.GLProfile"
     #D_ARGS="-Dnativewindow.debug.NativeWindow"
-    D_ARGS="-Djogl.debug.GLCanvas -Dnewt.debug.Window -Dnewt.debug.Display -Dnewt.debug.EDT -Djogl.debug.Animator"
+    #D_ARGS="-Djogl.debug.GLCanvas -Dnewt.debug.Window -Dnewt.debug.Display -Dnewt.debug.EDT -Djogl.debug.Animator"
     #D_ARGS="-Dnewt.debug.EDT -Dnewt.debug.Window -Djogl.debug.GLContext"
     #D_ARGS="-Dnativewindow.debug.X11Util.XErrorStackDump -Dnativewindow.debug.X11Util.TraceDisplayLifecycle -Dnativewindow.debug.X11Util"
     #D_ARGS="-Dnativewindow.debug.X11Util -Djogl.debug.GLContext -Djogl.debug.GLDrawable -Dnewt.debug=all"
@@ -164,10 +164,12 @@ function jrun() {
     #D_ARGS="-Dnewt.debug=all -Djogamp.debug.Lock -Djogamp.debug.Lock.TraceLock"
     #D_ARGS="-Djogl.debug.GLContext -Dnewt.debug=all -Djogamp.debug.Lock -Djogamp.common.utils.locks.Lock.timeout=10000"
     #D_ARGS="-Dnewt.debug=all"
+    D_ARGS="-Djogl.debug.GLCanvas -Djogl.debug.GLJPanel"
     #X_ARGS="-Dsun.java2d.noddraw=True -Dsun.java2d.opengl=True -Dsun.java2d.xrender=false"
     #X_ARGS="-Dsun.java2d.noddraw=True -Dsun.java2d.opengl=false -Dsun.java2d.xrender=false"
     #X_ARGS="-verbose:jni"
     #X_ARGS="-Xrs"
+    X_ARGS="-Dsun.awt.disableMixing=true"
 
     if [ $awton -eq 1 ] ; then
         export CLASSPATH=$JOGAMP_ALL_AWT_CLASSPATH
@@ -328,10 +330,6 @@ function testawtswt() {
 #testawt jogamp.newt.awt.opengl.VersionApplet $*
 #testawt javax.media.opengl.awt.GLCanvas $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestMainVersionGLCanvasAWT $*
-#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug551AWT $*
-#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug572AWT $*
-#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug611AWT $*
-#testawt com.jogamp.opengl.test.junit.jogl.awt.TestAWT01GLn $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestAWTCloseX11DisplayBug565 $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestSharedContextListAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestSharedContextNewtAWTBug523 $*
@@ -339,14 +337,20 @@ function testawtswt() {
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestPBufferDeadlockAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.TestShutdownCompleteAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.acore.x11.TestGLXCallsOnAWT $*
+#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug551AWT $*
+#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug572AWT $*
+#testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug611AWT $*
+#testawt com.jogamp.opengl.test.junit.jogl.awt.TestAWT01GLn $*
 #testawt com.jogamp.opengl.test.junit.jogl.awt.TestSwingAWT01GLn
 #testawt com.jogamp.opengl.test.junit.jogl.awt.TestAWT03GLCanvasRecreate01 $*
 #testawt com.jogamp.opengl.test.junit.jogl.awt.TestAWT02WindowClosing
+#testawt com.jogamp.opengl.test.junit.jogl.awt.TestJScrollPaneMixHwLw01AWT $*
+##testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug642JSplitPaneMixHwLw01AWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.awt.text.TestAWTTextRendererUseVertexArrayBug464
 #testawt com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.demos.es2.awt.TestGearsES2AWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsAWTAnalyzeBug455 $*
-#testawt com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsGLJPanelAWT $*
+testawt com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsGLJPanelAWT $*
 #testawt com.jogamp.opengl.test.junit.jogl.demos.gl2.awt.TestGearsGLJPanelAWTBug450 $*
 #testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug461FBOSupersamplingSwingAWT
 #testawt com.jogamp.opengl.test.junit.jogl.awt.TestBug461PBufferSupersamplingSwingAWT
@@ -370,7 +374,7 @@ function testawtswt() {
 #
 #testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTEclipseGLCanvas01GLn $*
 #testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTAccessor03AWTGLn $*
-testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTJOGLGLCanvas01GLn $*
+#testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTJOGLGLCanvas01GLn $*
 #testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestNewtCanvasSWTGLn $*
 #testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestNewtCanvasSWTBug628ResizeDeadlock $*
 #testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTBug643AsyncExec $*
@@ -416,10 +420,14 @@ testawtswt com.jogamp.opengl.test.junit.jogl.swt.TestSWTJOGLGLCanvas01GLn $*
 
 #testawt $*
 
+#testawtswt com.jogamp.opengl.test.junit.newt.parenting.TestParenting04SWT $*
+#testnoawt com.jogamp.opengl.test.junit.jogl.acore.TestInitConcurrent01NEWT $*
+
 #
 # Misc Utils
 #
 #testnoawt com.jogamp.opengl.test.junit.jogl.util.TestImmModeSinkES1NEWT $*
+#testnoawt com.jogamp.opengl.test.junit.jogl.util.TestImmModeSinkES2NEWT $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.util.TestES1FixedFunctionPipelineNEWT $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.demos.es1.newt.TestGearsES1NEWT $*
 #testnoawt com.jogamp.opengl.test.junit.jogl.demos.es1.newt.TestRedSquareES1NEWT $*
diff --git a/src/jogl/classes/com/jogamp/opengl/FBObject.java b/src/jogl/classes/com/jogamp/opengl/FBObject.java
index 40b45ead2..26c8ff77f 100644
--- a/src/jogl/classes/com/jogamp/opengl/FBObject.java
+++ b/src/jogl/classes/com/jogamp/opengl/FBObject.java
@@ -2283,7 +2283,8 @@ public class FBObject {
     /** Returns the framebuffer name to render to. */
     public final int getWriteFramebuffer() { return fbName; }
     /** Returns the framebuffer name to read from. Depending on multisampling, this may be a different framebuffer. */
-    public final int getReadFramebuffer() { return ( samples > 0 ) ? samplingSink.getReadFramebuffer() : fbName; }
+    public final int getReadFramebuffer() { return ( samples > 0 ) ? samplingSink.getReadFramebuffer() : fbName; }    
+    public final int getDefaultReadBuffer() { return GL.GL_COLOR_ATTACHMENT0; }    
     /** Return the number of color/texture attachments */
     public final int getColorAttachmentCount() { return colorAttachmentCount; }
     /** Return the stencil {@link RenderAttachment} attachment, if exist. Maybe share the same {@link Attachment#getName()} as {@link #getDepthAttachment()}, if packed depth-stencil is being used. */ 
diff --git a/src/jogl/classes/javax/media/opengl/GLBase.java b/src/jogl/classes/javax/media/opengl/GLBase.java
index 9bcee819a..82bb06b9c 100644
--- a/src/jogl/classes/javax/media/opengl/GLBase.java
+++ b/src/jogl/classes/javax/media/opengl/GLBase.java
@@ -432,6 +432,19 @@ public interface GLBase {
     * </p> 
     */
    public int getDefaultReadFramebuffer();
-
+   
+   /** 
+    * Returns the default color buffer within the current bound 
+    * {@link #getDefaultReadFramebuffer()}, i.e. GL_READ_FRAMEBUFFER​,  
+    * which will be used as the source for pixel reading commands, 
+    * like {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)} etc.
+    * <p>
+    * For offscreen framebuffer objects this is {@link GL#GL_COLOR_ATTACHMENT0},
+    * otherwise this is {@link GL#GL_FRONT} for single buffer configurations 
+    * and {@link GL#GL_BACK} for double buffer configurations.
+    * </p> 
+    */
+   public int getDefaultReadBuffer();
+   
 }
 
diff --git a/src/jogl/classes/javax/media/opengl/GLContext.java b/src/jogl/classes/javax/media/opengl/GLContext.java
index de10a2815..235003c38 100644
--- a/src/jogl/classes/javax/media/opengl/GLContext.java
+++ b/src/jogl/classes/javax/media/opengl/GLContext.java
@@ -970,6 +970,32 @@ public abstract class GLContext {
    */
   public abstract int getDefaultReadFramebuffer();
   
+  /** 
+   * Returns the default color buffer within the current bound 
+   * {@link #getDefaultReadFramebuffer()}, i.e. GL_READ_FRAMEBUFFER​,  
+   * which will be used as the source for pixel reading commands, 
+   * like {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)} etc.
+   * <p>
+   * For offscreen framebuffer objects this is {@link GL#GL_COLOR_ATTACHMENT0},
+   * otherwise this is {@link GL#GL_FRONT} for single buffer configurations 
+   * and {@link GL#GL_BACK} for double buffer configurations.
+   * </p> 
+   */
+  public abstract int getDefaultReadBuffer();
+  
+  /** On some platforms the mismatch between OpenGL's coordinate
+      system (origin at bottom left) and the window system's
+      coordinate system (origin at top left) necessitates a vertical
+      flip of pixels read from offscreen contexts.
+      <p>
+      Default impl. is <code>true</code>.
+      </p> 
+   */
+  public abstract boolean isGLOrientationFlippedVertical();
+  
+  /** Get the default pixel data type, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}. */
+  public abstract int getDefaultPixelDataType();
+  
   /**
    * @return The extension implementing the GLDebugOutput feature,
    *         either <i>GL_ARB_debug_output</i> or <i>GL_AMD_debug_output</i>.
diff --git a/src/jogl/classes/javax/media/opengl/GLFBODrawable.java b/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
index 079d9af5c..4d6c7c20e 100644
--- a/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
+++ b/src/jogl/classes/javax/media/opengl/GLFBODrawable.java
@@ -101,7 +101,8 @@ public interface GLFBODrawable extends GLDrawable {
     void setTextureUnit(int unit);
     
     /**
-     * Set a new sample size
+     * Set the number of sample buffers if using MSAA
+     * 
      * @param gl GL context object bound to this drawable, will be made current during operation. 
      *           A prev. current context will be make current after operation. 
      * @param newSamples new sample size
@@ -113,6 +114,25 @@ public interface GLFBODrawable extends GLDrawable {
      * @return the number of sample buffers if using MSAA, otherwise 0
      */
     int getNumSamples();
+        
+    /**
+     * Sets the number of buffers (FBO) being used if using {@link GLCapabilities#getDoubleBuffered() double buffering}.
+     * <p>
+     * If {@link GLCapabilities#getDoubleBuffered() double buffering} is not chosen, this is a NOP.
+     * </p>
+     * <p>
+     * Must be called before {@link #isInitialized() initialization}, otherwise an exception is thrown.
+     * </p>
+     * @return the new number of buffers (FBO) used, maybe different than the requested <code>bufferCount</code> (see above) 
+     * @throws GLException if already initialized, see {@link #isInitialized()}.
+     */
+    int setNumBuffers(int bufferCount) throws GLException;
+    
+    /** 
+     * @return the number of buffers (FBO) being used. 1 if not using {@link GLCapabilities#getDoubleBuffered() double buffering},
+     * otherwise &ge; 2, depending on {@link #setNumBuffers(int)}. 
+     */
+    int getNumBuffers();
     
     /**
      * @return the used {@link DoubleBufferMode} 
diff --git a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
index dcfc1f0dd..a9d4989dc 100644
--- a/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
+++ b/src/jogl/classes/javax/media/opengl/awt/GLJPanel.java
@@ -618,12 +618,18 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
 
   @Override
   public NativeSurface getNativeSurface() {
-    throw new GLException("FIXME");
+    if(null != backend) {
+        return backend.getDrawable().getNativeSurface();
+    }
+    return null;
   }
 
   @Override
   public long getHandle() {
-    throw new GLException("FIXME");
+    if(null != backend) {
+        return backend.getDrawable().getNativeSurface().getSurfaceHandle();
+    }
+    return 0;
   }
 
   @Override
@@ -657,6 +663,8 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
         if (oglPipelineEnabled) {
           backend = new J2DOGLBackend();
         } else {
+          backend = new SoftwareBackend();
+          /**
           if (!hardwareAccelerationDisabled &&
               factory.canCreateGLPbuffer(null)) {
             backend = new PbufferBackend();
@@ -665,7 +673,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
               throw new GLException("Fallback to software rendering disabled by user");
             }
             backend = new SoftwareBackend();
-          }
+          } */
         }
       }
 
@@ -996,7 +1004,7 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
           gl.glPixelStorei(GL2.GL_PACK_ALIGNMENT,     1);
 
           // Actually read the pixels.
-          gl.glReadBuffer(GL2.GL_FRONT);
+          gl.glReadBuffer(gl.getDefaultReadBuffer());
           if (readBackBytes != null) {
             gl.glReadPixels(0, 0, readBackWidthInPixels, readBackHeightInPixels, glFormat, glType, readBackBytes);
           } else if (readBackInts != null) {
@@ -1173,12 +1181,12 @@ public class GLJPanel extends JPanel implements AWTGLAutoDrawable, WindowClosing
 
     @Override
     protected int getGLPixelType() {
-      return offscreenContext.getOffscreenContextPixelDataType();
+      return offscreenContext.getDefaultPixelDataType();
     }
 
     @Override
     protected boolean flipVertically() {
-      return offscreenContext.offscreenImageNeedsVerticalFlip();
+      return offscreenContext.isGLOrientationFlippedVertical();
     }
   }
 
diff --git a/src/jogl/classes/jogamp/opengl/GLContextImpl.java b/src/jogl/classes/jogamp/opengl/GLContextImpl.java
index 65b523394..24fc466b1 100644
--- a/src/jogl/classes/jogamp/opengl/GLContextImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLContextImpl.java
@@ -1513,15 +1513,46 @@ public abstract class GLContextImpl extends GLContext {
     throw new GLException("Not supported on non-pbuffer contexts");
   }
 
-  /** On some platforms the mismatch between OpenGL's coordinate
-      system (origin at bottom left) and the window system's
-      coordinate system (origin at top left) necessitates a vertical
-      flip of pixels read from offscreen contexts. */
-  public abstract boolean offscreenImageNeedsVerticalFlip();
+  @Override
+  public boolean isGLOrientationFlippedVertical() {
+      return true;
+  }
 
-  /** Only called for offscreen contexts; needed by glReadPixels */
-  public abstract int getOffscreenContextPixelDataType();
+  @Override
+  public int getDefaultPixelDataType() {
+      if(!pixelDataTypeEvaluated) {
+          synchronized(this) {
+              if(!pixelDataTypeEvaluated) {
+                  evalPixelDataType();
+                  pixelDataTypeEvaluated = true;
+              }
+          }
+      }
+      return pixelDataType;
+  }
 
+  private volatile boolean pixelDataTypeEvaluated = false; 
+  int /* pixelDataInternalFormat, */ pixelDataFormat, pixelDataType;
+  
+  private final void evalPixelDataType() {
+    /* if(isGL2GL3() && 3 == components) {
+        pixelDataInternalFormat=GL.GL_RGB;
+        pixelDataFormat=GL.GL_RGB;
+        pixelDataType = GL.GL_UNSIGNED_BYTE;            
+    } else */ if(isGLES2Compatible() || isExtensionAvailable(GLExtensions.OES_read_format)) {
+        final int[] glImplColorReadVals = new int[] { 0, 0 };
+        gl.glGetIntegerv(GL.GL_IMPLEMENTATION_COLOR_READ_FORMAT, glImplColorReadVals, 0);
+        gl.glGetIntegerv(GL.GL_IMPLEMENTATION_COLOR_READ_TYPE, glImplColorReadVals, 1);            
+        // pixelDataInternalFormat = (4 == components) ? GL.GL_RGBA : GL.GL_RGB;
+        pixelDataFormat = glImplColorReadVals[0];
+        pixelDataType = glImplColorReadVals[1];
+    } else {
+        // RGBA read is safe for all GL profiles 
+        // pixelDataInternalFormat = (4 == components) ? GL.GL_RGBA : GL.GL_RGB;
+        pixelDataFormat=GL.GL_RGBA;
+        pixelDataType = GL.GL_UNSIGNED_BYTE;
+    }            
+  }
 
   //----------------------------------------------------------------------
   // Helpers for buffer object optimizations
@@ -1599,8 +1630,10 @@ public abstract class GLContextImpl extends GLContext {
   @Override
   public final int getDefaultDrawFramebuffer() { return drawable.getDefaultDrawFramebuffer(); }  
   @Override
-  public final int getDefaultReadFramebuffer() { return drawable.getDefaultReadFramebuffer(); }
-  
+  public final int getDefaultReadFramebuffer() { return drawable.getDefaultReadFramebuffer(); }  
+  @Override
+  public final int getDefaultReadBuffer() { return drawable.getDefaultReadBuffer(gl); }
+    
   //---------------------------------------------------------------------------
   // GL_ARB_debug_output, GL_AMD_debug_output helpers
   //
diff --git a/src/jogl/classes/jogamp/opengl/GLDrawableImpl.java b/src/jogl/classes/jogamp/opengl/GLDrawableImpl.java
index df7f742aa..ccf0a8f0d 100644
--- a/src/jogl/classes/jogamp/opengl/GLDrawableImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLDrawableImpl.java
@@ -244,7 +244,16 @@ public abstract class GLDrawableImpl implements GLDrawable {
   /** Callback for special implementations, allowing GLContext to fetch a custom default render framebuffer. Defaults to zero.*/
   protected int getDefaultDrawFramebuffer() { return 0; }
   /** Callback for special implementations, allowing GLContext to fetch a custom default read framebuffer. Defaults to zero. */
-  protected int getDefaultReadFramebuffer() { return 0; }
+  protected int getDefaultReadFramebuffer() { return 0; }  
+  /** Callback for special implementations, allowing GLContext to fetch a custom default read buffer of current framebuffer. */
+  protected int getDefaultReadBuffer(GL gl) {
+      if(gl.isGLES() || getChosenGLCapabilities().getDoubleBuffered()) {
+          // Note-1: Neither ES1 nor ES2 supports selecting the read buffer via glReadBuffer
+          // Note-2: ES3 only supports GL_BACK, GL_NONE or GL_COLOR_ATTACHMENT0+i
+          return GL.GL_BACK;
+      }
+      return GL.GL_FRONT ; 
+  }
   
   @Override
   public final synchronized boolean isRealized() {
diff --git a/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java b/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
index 7a468a41e..b72f79868 100644
--- a/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLFBODrawableImpl.java
@@ -302,6 +302,9 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
     protected final int getDefaultReadFramebuffer() { return initialized ? fbos[fboIFront].getReadFramebuffer() : 0; }
 
     @Override
+    protected final int getDefaultReadBuffer(GL gl) { return initialized ? fbos[fboIFront].getDefaultReadBuffer() : GL.GL_COLOR_ATTACHMENT0 ; }
+    
+    @Override
     protected final void setRealizedImpl() {
         final MutableGraphicsConfiguration msConfig = (MutableGraphicsConfiguration) surface.getGraphicsConfiguration();
         if(realized) {
@@ -435,6 +438,17 @@ public class GLFBODrawableImpl extends GLDrawableImpl implements GLFBODrawable {
         }
     }
     
+    @Override
+    public final int setNumBuffers(int bufferCount) throws GLException {
+        // FIXME: Implement
+        return bufferCount;
+    }
+    
+    @Override
+    public final int getNumBuffers() {
+        return bufferCount;
+    }
+    
     /** // TODO: Add or remove TEXTURE (only) DoubleBufferMode support
     @Override
     public final DoubleBufferMode getDoubleBufferMode() {
diff --git a/src/jogl/classes/jogamp/opengl/GLOffscreenAutoDrawableImpl.java b/src/jogl/classes/jogamp/opengl/GLOffscreenAutoDrawableImpl.java
index 7701f209f..59a00170d 100644
--- a/src/jogl/classes/jogamp/opengl/GLOffscreenAutoDrawableImpl.java
+++ b/src/jogl/classes/jogamp/opengl/GLOffscreenAutoDrawableImpl.java
@@ -95,6 +95,16 @@ public class GLOffscreenAutoDrawableImpl extends GLAutoDrawableDelegate implemen
             windowRepaintOp();
         }
         
+        @Override
+        public final int setNumBuffers(int bufferCount) throws GLException {
+            return ((GLFBODrawableImpl)drawable).setNumBuffers(bufferCount);
+        }
+        
+        @Override
+        public final int getNumBuffers() {
+            return ((GLFBODrawableImpl)drawable).getNumBuffers();
+        }
+        
         /** // TODO: Add or remove TEXTURE (only) DoubleBufferMode support
         @Override
         public DoubleBufferMode getDoubleBufferMode() {
diff --git a/src/jogl/classes/jogamp/opengl/egl/EGLContext.java b/src/jogl/classes/jogamp/opengl/egl/EGLContext.java
index 84aeaa94a..deb3813b1 100644
--- a/src/jogl/classes/jogamp/opengl/egl/EGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/egl/EGLContext.java
@@ -344,14 +344,4 @@ public abstract class EGLContext extends GLContextImpl {
     public ByteBuffer glAllocateMemoryNV(int arg0, float arg1, float arg2, float arg3) {
         throw new GLException("Should not call this");
     }
-
-    @Override
-    public boolean offscreenImageNeedsVerticalFlip() {
-        throw new GLException("Should not call this");
-    }
-
-    @Override
-    public int getOffscreenContextPixelDataType() {
-        throw new GLException("Should not call this");
-    }
 }
diff --git a/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXCGLContext.java b/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXCGLContext.java
index cde9841b8..63ed2ab7d 100644
--- a/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXCGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXCGLContext.java
@@ -420,20 +420,6 @@ public abstract class MacOSXCGLContext extends GLContextImpl
     return super.isExtensionAvailable(glExtensionName);
   }
 
-  @Override
-  public int getOffscreenContextPixelDataType() {
-    throw new GLException("Should not call this");
-  }
-
-  public int getOffscreenContextReadBuffer() {
-    throw new GLException("Should not call this");
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
-    throw new GLException("Should not call this");
-  }
-
   // Support for "mode switching" as described in MacOSXCGLDrawable
   public void setOpenGLMode(GLBackendType mode) {
       if (mode == openGLMode) {
diff --git a/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXOffscreenCGLContext.java b/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXOffscreenCGLContext.java
index 7b13ce22e..f2e636796 100644
--- a/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXOffscreenCGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/macosx/cgl/MacOSXOffscreenCGLContext.java
@@ -49,18 +49,8 @@ public class MacOSXOffscreenCGLContext extends MacOSXPbufferCGLContext
   }
 
   @Override
-  public int getOffscreenContextPixelDataType() {
-    GL gl = getGL();
+  public int getDefaultPixelDataType() {
+    final GL gl = getGL();
     return gl.isGL2GL3()?GL2GL3.GL_UNSIGNED_INT_8_8_8_8_REV:GL.GL_UNSIGNED_SHORT_5_5_5_1;
   }
-
-  @Override
-  public int getOffscreenContextReadBuffer() {
-    return GL.GL_FRONT;
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
-    return true;
-  }
 }
diff --git a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsBitmapWGLContext.java b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsBitmapWGLContext.java
index 51341a098..c8aac7f7b 100644
--- a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsBitmapWGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsBitmapWGLContext.java
@@ -49,18 +49,12 @@ public class WindowsBitmapWGLContext extends WindowsWGLContext {
   }
 
   @Override
-  public int getOffscreenContextPixelDataType() {
+  public int getDefaultPixelDataType() {
       return GL.GL_UNSIGNED_BYTE;
   }
 
   @Override
-  public int getOffscreenContextReadBuffer() {
-    // On Windows these contexts are always single-buffered
-    return GL.GL_FRONT;
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
+  public boolean isGLOrientationFlippedVertical() {
     // We can take care of this in the DIB creation (see below)
     return false;
   }
diff --git a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
index 57f16522c..92d75e3fd 100644
--- a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
@@ -538,20 +538,6 @@ public class WindowsWGLContext extends GLContextImpl {
   }
 
   @Override
-  public int getOffscreenContextPixelDataType() {
-    throw new GLException("Should not call this");
-  }
-
-  public int getOffscreenContextReadBuffer() {
-    throw new GLException("Should not call this");
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
-    throw new GLException("Should not call this");
-  }
-
-  @Override
   public void bindPbufferToTexture() {
     throw new GLException("Should not call this");
   }
diff --git a/src/jogl/classes/jogamp/opengl/x11/glx/X11GLXContext.java b/src/jogl/classes/jogamp/opengl/x11/glx/X11GLXContext.java
index 76e0bc15c..bf1045132 100644
--- a/src/jogl/classes/jogamp/opengl/x11/glx/X11GLXContext.java
+++ b/src/jogl/classes/jogamp/opengl/x11/glx/X11GLXContext.java
@@ -619,20 +619,6 @@ public abstract class X11GLXContext extends GLContextImpl {
   }
 
   @Override
-  public int getOffscreenContextPixelDataType() {
-    throw new GLException("Should not call this");
-  }
-
-  public int getOffscreenContextReadBuffer() {
-    throw new GLException("Should not call this");
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
-    throw new GLException("Should not call this");
-  }
-
-  @Override
   public void bindPbufferToTexture() {
     throw new GLException("Should not call this");
   }
diff --git a/src/jogl/classes/jogamp/opengl/x11/glx/X11PixmapGLXContext.java b/src/jogl/classes/jogamp/opengl/x11/glx/X11PixmapGLXContext.java
index 96d0f18dc..1cfb7e427 100644
--- a/src/jogl/classes/jogamp/opengl/x11/glx/X11PixmapGLXContext.java
+++ b/src/jogl/classes/jogamp/opengl/x11/glx/X11PixmapGLXContext.java
@@ -50,24 +50,9 @@ public class X11PixmapGLXContext extends X11GLXContext {
   }
 
   @Override
-  public int getOffscreenContextPixelDataType() {
+  public int getDefaultPixelDataType() {
     GL gl = getGL();
     return gl.isGL2GL3()?GL2GL3.GL_UNSIGNED_INT_8_8_8_8_REV:GL.GL_UNSIGNED_SHORT_5_5_5_1;
   }
 
-  @Override
-  public int getOffscreenContextReadBuffer() {
-    GLCapabilitiesImmutable caps = (GLCapabilitiesImmutable)drawable.getNativeSurface().getGraphicsConfiguration().getChosenCapabilities();
-    if (caps.getDoubleBuffered()) {
-      return GL.GL_BACK;
-    }
-    return GL.GL_FRONT;
-  }
-
-  @Override
-  public boolean offscreenImageNeedsVerticalFlip() {
-    // There doesn't seem to be a way to do this in the construction
-    // of the Pixmap or GLXPixmap
-    return true;
-  }
 }