bpo-34120: fix IDLE freezing after closing dialogs (GH-8603)

Added missing .grab_release() calls to all places where we call .grab_set().
diff --git a/Lib/idlelib/textview.py b/Lib/idlelib/textview.py
index d9260e6..e78e297 100644
--- a/Lib/idlelib/textview.py
+++ b/Lib/idlelib/textview.py
@@ -91,6 +91,7 @@
 
     def ok(self, event=None):
         """Dismiss text viewer dialog."""
+        self.grab_release()
         self.destroy()