[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/configHelpSourceEdit.py b/Lib/idlelib/configHelpSourceEdit.py
index 5816449..62b010a 100644
--- a/Lib/idlelib/configHelpSourceEdit.py
+++ b/Lib/idlelib/configHelpSourceEdit.py
@@ -155,10 +155,12 @@
                     # Mac Safari insists on using the URI form for local files
                     self.result = list(self.result)
                     self.result[1] = "file://" + path
+            self.grab_release()
             self.destroy()
 
     def Cancel(self, event=None):
         self.result = None
+        self.grab_release()
         self.destroy()
 
 if __name__ == '__main__':