Fix a regression in 0.10 that caused incorrect rendering of the status bar in irssi when used inside screen.

Fixes #621. The cursor in margin check was incorrect causing upwards
movement of the cursor when below the bottom margin to be incorrect.

docs/changelog.rst

@@ -86,6 +86,9 @@ Changelog
 - Fix `kitty @ set-colors` not working with the window border colors.
   (:iss:`623`)
 
+- Fix a regression in 0.10 that caused incorrect rendering of the status bar in
+  irssi when used inside screen. (:iss:`621`)
+
 
 0.10.1 [2018-05-24]
 ------------------------------

kitty/screen.c

@@ -464,7 +464,7 @@ write_escape_code_to_child(Screen *self, unsigned char which, const char *data)
 
 static inline bool
 cursor_within_margins(Screen *self) {
-    return self->margin_top <= self->cursor->y && self->cursor->y >= self->margin_bottom;
+    return self->margin_top <= self->cursor->y && self->cursor->y <= self->margin_bottom;
 }
 
 void

kitty_tests/screen.py

@@ -319,11 +319,15 @@ def nl():
             s.reset_mode(DECOM)
         # Test that moving cursor outside the margins works as expected
         s = self.create_screen(10, 10)
-        s.set_margins(5, 7)
+        s.set_margins(4, 6)
         s.cursor_position(0, 0)
         self.ae(s.cursor.y, 0)
         nl()
         self.ae(s.cursor.y, 1)
+        s.cursor.y = s.lines - 1
+        self.ae(s.cursor.y, 9)
+        s.reverse_index()
+        self.ae(s.cursor.y, 8)
 
     def test_sgr(self):
         s = self.create_screen()