The splits layout needs its own draw_minimal_borders implementation

docs/changelog.rst

@@ -4,6 +4,13 @@ Changelog
 |kitty| is a feature full, cross-platform, *fast*, GPU based terminal emulator.
 To update |kitty|, :doc:`follow the instructions <binary>`.
 
+0.17.2 [future]
+--------------------
+
+- Fix a regression in 0.17 that broke drawing of borders with non-minimal
+  borders (:iss:`2474`)
+
+
 0.17.1 [2020-03-24]
 --------------------
 

kitty/layout.py

@@ -1512,6 +1512,13 @@ def swap_windows_in_layout(self, all_windows: WindowList, a: int, b: int) -> Non
                 else:
                     p2.two = w1
 
+    def minimal_borders(self, windows: WindowList, active_window: Optional[WindowType], needs_borders_map: Dict[int, bool]) -> Generator[Borders, None, None]:
+        for w in windows:
+            if (w is active_window and draw_active_borders) or w.needs_attention:
+                yield all_borders
+            else:
+                yield no_borders
+
     def layout_action(self, action_name: str, args: Sequence[str], all_windows: WindowList, active_window_idx: int) -> Optional[Union[bool, int]]:
         if action_name == 'rotate':
             args = args or ('90',)