8221261: Deadlock on macOS in JFXPanel app when handling IME calls

src/java.desktop/macosx/classes/sun/lwawt/macosx/CInputMethod.java

@@ -623,7 +623,7 @@ public void run() { synchronized(retString) {
 
                     retString[0] = new String(selectedText);
                 }}
-            }, fAwtFocussedComponent);
+            }, fAwtFocussedComponent, true);
         } catch (InvocationTargetException ite) { ite.printStackTrace(); }
 
         synchronized(retString) { return retString[0]; }
@@ -671,7 +671,7 @@ public void run() { synchronized(returnValue) {
                     returnValue[1] = theIterator.getEndIndex() - theIterator.getBeginIndex();
 
                 }}
-            }, fAwtFocussedComponent);
+            }, fAwtFocussedComponent, true);
         } catch (InvocationTargetException ite) { ite.printStackTrace(); }
 
         synchronized(returnValue) { return returnValue; }
@@ -696,7 +696,7 @@ public void run() { synchronized(returnValue) {
                     // insert spot less the length of the composed text.
                     returnValue[0] = fIMContext.getInsertPositionOffset();
                 }}
-            }, fAwtFocussedComponent);
+            }, fAwtFocussedComponent, true);
         } catch (InvocationTargetException ite) { ite.printStackTrace(); }
 
         returnValue[1] = fCurrentTextLength;
@@ -743,7 +743,7 @@ public void run() { synchronized(rect) {
                         }
                     }
                 }}
-            }, fAwtFocussedComponent);
+            }, fAwtFocussedComponent, true);
         } catch (InvocationTargetException ite) { ite.printStackTrace(); }
 
         synchronized(rect) { return rect; }
@@ -763,7 +763,7 @@ public void run() { synchronized(offsetInfo) {
                     offsetInfo[0] = fIMContext.getLocationOffset(screenX, screenY);
                     insertPositionOffset[0] = fIMContext.getInsertPositionOffset();
                 }}
-            }, fAwtFocussedComponent);
+            }, fAwtFocussedComponent, true);
         } catch (InvocationTargetException ite) { ite.printStackTrace(); }
 
         // This bit of gymnastics ensures that the returned location is within the composed text.

src/java.desktop/macosx/classes/sun/lwawt/macosx/LWCToolkit.java

@@ -720,6 +720,25 @@ public T getResult() throws Exception {
      */
     public static void invokeAndWait(Runnable runnable, Component component)
             throws InvocationTargetException {
+        invokeAndWait(runnable, component, false);
+    }
+
+    /**
+     * Package-scope version of invokeAndWait that takes a processEvents
+     * flag to decide whether to dispatch native events while in the loop.
+     * Currently, only the IME handlers set processEvents to true. See
+     * the warning in doAWTRunLoop about using this flag.
+     *
+     * Kicks an event over to the appropriate event queue and waits for it to
+     * finish To avoid deadlocking, we manually run the NSRunLoop while waiting
+     * Any selector invoked using ThreadUtilities performOnMainThread will be
+     * processed in doAWTRunLoop The InvocationEvent will call
+     * LWCToolkit.stopAWTRunLoop() when finished, which will stop our manual
+     * run loop. Does not dispatch native events while in the loop unless
+     * the processEvents flag is set to true.
+     */
+    static void invokeAndWait(Runnable runnable, Component component, boolean processEvents)
+            throws InvocationTargetException {
         Objects.requireNonNull(component, "Null component provided to invokeAndWait");
 
         long mediator = createAWTRunLoopMediator();
@@ -737,7 +756,7 @@ public static void invokeAndWait(Runnable runnable, Component component)
         SunToolkit.postEvent(appContext, invocationEvent);
         // 3746956 - flush events from PostEventQueue to prevent them from getting stuck and causing a deadlock
         SunToolkit.flushPendingEvents(appContext);
-        doAWTRunLoop(mediator, false);
+        doAWTRunLoop(mediator, processEvents);
 
         checkException(invocationEvent);
     }
@@ -927,7 +946,7 @@ public boolean canPopupOverlapTaskBar() {
      * Method to run a nested run-loop. The nested loop is spinned in the javaRunLoop mode, so selectors sent
      * by [JNFRunLoop performOnMainThreadWaiting] are processed.
      * @param mediator a native pointer to the mediator object created by createAWTRunLoopMediator
-     * @param processEvents if true - dispatches event while in the nested loop. Used in DnD.
+     * @param processEvents if true - dispatches event while in the nested loop. Used in DnD and IME.
      *                      Additional attention is needed when using this feature as we short-circuit normal event
      *                      processing which could break Appkit.
      *                      (One known example is when the window is resized with the mouse)