bpo-17535: Increase line number horizontal padding by 2 pixels (GH-14959)

diff --git a/Lib/idlelib/sidebar.py b/Lib/idlelib/sidebar.py
index 8f9bf80..76964a4 100644
--- a/Lib/idlelib/sidebar.py
+++ b/Lib/idlelib/sidebar.py
@@ -51,7 +51,7 @@
 
         _padx, pady = get_widget_padding(self.text)
         self.sidebar_text = tk.Text(self.parent, width=1, wrap=tk.NONE,
-                                    padx=0, pady=pady,
+                                    padx=2, pady=pady,
                                     borderwidth=0, highlightthickness=0)
         self.sidebar_text.config(state=tk.DISABLED)
         self.text['yscrollcommand'] = self.redirect_yscroll_event