bpo-1529353: IDLE: squeeze large output in the shell (GH-7626)

diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index 52c11e3..5458c59 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -856,6 +856,10 @@
         ("help", "_Help"),
     ]
 
+    # Extend right-click context menu
+    rmenu_specs = OutputWindow.rmenu_specs + [
+        ("Squeeze", "<<squeeze-current-text>>"),
+    ]
 
     # New classes
     from idlelib.history import History