attempt to fix tests failing on Linux

There is apparently a minor inconsistency in Tk's Text widget.

Author: taleinat

Lib/idlelib/idle_test/test_linenumbers.py

@@ -179,16 +179,16 @@ def get_width():
         self.assert_sidebar_n_lines(99)
         self.assertEqual(get_width(), 2)
 
-        self.text.delete('50.0', 'end')
+        self.text.delete('50.0 -1c', 'end -1c')
         self.assert_sidebar_n_lines(49)
         self.assertEqual(get_width(), 2)
 
-        self.text.delete('5.0', 'end')
+        self.text.delete('5.0 -1c', 'end -1c')
         self.assert_sidebar_n_lines(4)
         self.assertEqual(get_width(), 1)
 
         # note: Text widgets always keep a single '\n' character at the end
-        self.text.delete('1.0', 'end')
+        self.text.delete('1.0', 'end -1c')
         self.assert_sidebar_n_lines(1)
         self.assertEqual(get_width(), 1)
 

Lib/idlelib/linenumbers.py

@@ -250,9 +250,9 @@ def update_sidebar_text(self, end):
                 [''],
                 map(str, range(self.prev_end + 1, end + 1)),
             ))
-            self.sidebar_text.insert(f'{end+1:d}.0', new_text, 'linenumber')
+            self.sidebar_text.insert(f'end -1c', new_text, 'linenumber')
         else:
-            self.sidebar_text.delete(f'{end+1:d}.0', 'end')
+            self.sidebar_text.delete(f'{end+1}.0 -1c', 'end -1c')
         self.sidebar_text.config(state=tk.DISABLED)
 
         self.prev_end = end