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

Added missing .grab_release() calls to all places where we call .grab_set().

(cherry picked from commit 10ea9409ceb5da83cb380b610750551e26561044)
diff --git a/Lib/idlelib/textView.py b/Lib/idlelib/textView.py
index b8c4ac1..ec837f8 100644
--- a/Lib/idlelib/textView.py
+++ b/Lib/idlelib/textView.py
@@ -39,7 +39,8 @@
         self.textView.insert(0.0, text)
         self.textView.config(state=DISABLED)
 
-        if modal:
+        self.is_modal = modal
+        if self.is_modal:
             self.transient(parent)
             self.grab_set()
             self.wait_window()
@@ -62,6 +63,8 @@
         frameText.pack(side=TOP,expand=TRUE,fill=BOTH)
 
     def Ok(self, event=None):
+        if self.is_modal:
+            self.grab_release()
         self.destroy()