3 files changed, 54 insertions, 0 deletions
diff --git a/src/classes/com/sun/opengl/impl/macosx/MacOSXExternalGLContext.java b/src/classes/com/sun/opengl/impl/macosx/MacOSXExternalGLContext.java
index 7a0b53a98..ceda14f3b 100644
--- a/src/classes/com/sun/opengl/impl/macosx/MacOSXExternalGLContext.java
+++ b/src/classes/com/sun/opengl/impl/macosx/MacOSXExternalGLContext.java
@@ -45,6 +45,7 @@ import com.sun.opengl.impl.*;
 public class MacOSXExternalGLContext extends MacOSXGLContext {
   private boolean firstMakeCurrent = true;
   private boolean created = true;
+  private GLContext lastContext;
 
   public MacOSXExternalGLContext() {
     super(null, null);
@@ -74,6 +75,23 @@ public class MacOSXExternalGLContext extends MacOSXGLContext {
     return true;
   }
 
+  public int makeCurrent() throws GLException {
+    // Save last context if necessary to allow external GLContexts to
+    // talk to other GLContexts created by this library
+    GLContext cur = getCurrent();
+    if (cur != null && cur != this) {
+      lastContext = cur;
+      setCurrent(null);
+    }
+    return super.makeCurrent();
+  }  
+
+  public void release() throws GLException {
+    super.release();
+    setCurrent(lastContext);
+    lastContext = null;
+  }
+
   protected int makeCurrentImpl() throws GLException {
     if (firstMakeCurrent) {
       firstMakeCurrent = false;
diff --git a/src/classes/com/sun/opengl/impl/windows/WindowsExternalGLContext.java b/src/classes/com/sun/opengl/impl/windows/WindowsExternalGLContext.java
index cd51f4eb1..a73cc7ac4 100755
--- a/src/classes/com/sun/opengl/impl/windows/WindowsExternalGLContext.java
+++ b/src/classes/com/sun/opengl/impl/windows/WindowsExternalGLContext.java
@@ -47,6 +47,7 @@ import com.sun.opengl.impl.*;
 public class WindowsExternalGLContext extends WindowsGLContext {
   private boolean firstMakeCurrent = true;
   private boolean created = true;
+  private GLContext lastContext;
 
   public WindowsExternalGLContext() {
     super(null, null, true);
@@ -61,6 +62,23 @@ public class WindowsExternalGLContext extends WindowsGLContext {
     resetGLFunctionAvailability();
   }
 
+  public int makeCurrent() throws GLException {
+    // Save last context if necessary to allow external GLContexts to
+    // talk to other GLContexts created by this library
+    GLContext cur = getCurrent();
+    if (cur != null && cur != this) {
+      lastContext = cur;
+      setCurrent(null);
+    }
+    return super.makeCurrent();
+  }  
+
+  public void release() throws GLException {
+    super.release();
+    setCurrent(lastContext);
+    lastContext = null;
+  }
+
   protected int makeCurrentImpl() throws GLException {
     if (firstMakeCurrent) {
       firstMakeCurrent = false;
diff --git a/src/classes/com/sun/opengl/impl/x11/X11ExternalGLContext.java b/src/classes/com/sun/opengl/impl/x11/X11ExternalGLContext.java
index 80d9c6f1a..89b769eee 100755
--- a/src/classes/com/sun/opengl/impl/x11/X11ExternalGLContext.java
+++ b/src/classes/com/sun/opengl/impl/x11/X11ExternalGLContext.java
@@ -45,6 +45,7 @@ import com.sun.opengl.impl.*;
 public class X11ExternalGLContext extends X11GLContext {
   private boolean firstMakeCurrent = true;
   private boolean created = true;
+  private GLContext lastContext;
 
   public X11ExternalGLContext() {
     super(null, null);
@@ -65,6 +66,23 @@ public class X11ExternalGLContext extends X11GLContext {
   protected void create() {
   }
 
+  public int makeCurrent() throws GLException {
+    // Save last context if necessary to allow external GLContexts to
+    // talk to other GLContexts created by this library
+    GLContext cur = getCurrent();
+    if (cur != null && cur != this) {
+      lastContext = cur;
+      setCurrent(null);
+    }
+    return super.makeCurrent();
+  }  
+
+  public void release() throws GLException {
+    super.release();
+    setCurrent(lastContext);
+    lastContext = null;
+  }
+
   protected int makeCurrentImpl() throws GLException {
     mostRecentDisplay = drawable.getDisplay();
     if (firstMakeCurrent) {