src/macosx/classes/sun/lwawt/macosx/CEmbeddedFrame.java

@@ -37,10 +37,11 @@
 public class CEmbeddedFrame extends EmbeddedFrame {
 
     private CPlatformResponder responder;
     private static final Object classLock = new Object();
     private static volatile CEmbeddedFrame focusedWindow;
+    private CEmbeddedFrame previousFocusedWindow;
     private boolean parentWindowActive = true;
 
     public CEmbeddedFrame() {
         show();
     }

@@ -143,10 +144,29 @@
     // handleWindowFocusEvent is called for all applets, when the browser
     // becomes active/inactive. This event should be filtered out for
     // non-focused applet. This method can be called from different threads.
     public void handleWindowFocusEvent(boolean parentWindowActive) {
         this.parentWindowActive = parentWindowActive;
+        // If several applets are running in different browser's windows, it is necessary to
+        // detect the switching between the parent windows and update focusedWindow accordingly.
+        synchronized (classLock) {
+            if (!parentWindowActive) {
+                this.previousFocusedWindow = focusedWindow;
+            }
+            if (parentWindowActive && focusedWindow != this &&
+                (focusedWindow == null || (focusedWindow != null && !focusedWindow.isParentWindowActive()))) {
+                // It looks like we have switched to another browser window, let's restore focus to
+                // the previously focused applet in this window.
+                if (this.previousFocusedWindow != null) {
+                    focusedWindow = this.previousFocusedWindow;
+                } else {
+                    // No applets were focused in this window, so set focus to the first
+                    // applet in the window
+                    focusedWindow = this;
+                }
+            }
+        }
         // ignore focus "lost" native request as it may mistakenly
         // deactivate active window (see 8001161)
         if (focusedWindow == this && parentWindowActive) {
             responder.handleWindowFocusEvent(parentWindowActive, null);
         }