Avoid extraneous calls to the UI thread

* java/org/gnu/emacs/EmacsView.java (EmacsView)
(showOnScreenKeyboard, hideOnScreenKeyboard)
(onCheckIsTextEditor): Make synchronized.
* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow)
(toggleOnScreenKeyboard): Don't post to the main thread.

java/org/gnu/emacs/EmacsView.java

@@ -590,7 +590,7 @@ public final class EmacsView extends ViewGroup
     super.onAttachedToWindow ();
   }
 
-  public void
+  public synchronized void
   showOnScreenKeyboard ()
   {
     /* Specifying no flags at all tells the system the user asked for
@@ -599,7 +599,7 @@ public final class EmacsView extends ViewGroup
     isCurrentlyTextEditor = true;
   }
 
-  public void
+  public synchronized void
   hideOnScreenKeyboard ()
   {
     imManager.hideSoftInputFromWindow (this.getWindowToken (),
@@ -686,7 +686,7 @@ public final class EmacsView extends ViewGroup
   }
 
   @Override
-  public boolean
+  public synchronized boolean
   onCheckIsTextEditor ()
   {
     /* If value is true, then the system will display the on screen