When re-attaching a detached tab preserve internal layout state such as biases and orientations

Fixes kovidgoyal#8106

Author: kovidgoyal

docs/changelog.rst

@@ -109,6 +109,8 @@ Detailed list of changes
 
 - Fix enlarging window when a long line is wrapped between the first line of the scrollback buffer and the screen inserting a spurious newline (:iss:`7033`)
 
+- When re-attaching a detached tab preserve internal layout state such as biases and orientations (:iss:`8106`)
+
 0.37.0 [2024-10-30]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

kitty/layout/base.py

@@ -223,9 +223,7 @@ class Layout:
     only_active_window_visible = False
 
     def __init__(self, os_window_id: int, tab_id: int, layout_opts: str = '') -> None:
-        self.os_window_id = os_window_id
-        self.tab_id = tab_id
-        self.set_active_window_in_os_window = partial(set_active_window, os_window_id, tab_id)
+        self.set_owner(os_window_id, tab_id)
         # A set of rectangles corresponding to the blank spaces at the edges of
         # this layout, i.e. spaces that are not covered by any window
         self.blank_rects: List[Rect] = []
@@ -234,6 +232,12 @@ def __init__(self, os_window_id: int, tab_id: int, layout_opts: str = '') -> Non
         self.full_name = f'{self.name}:{layout_opts}' if layout_opts else self.name
         self.remove_all_biases()
 
+    def set_owner(self, os_window_id: int, tab_id: int) -> None:
+        # Useful when moving a layout from one tab to another typically a detached tab being re-attached
+        self.os_window_id = os_window_id
+        self.tab_id = tab_id
+        self.set_active_window_in_os_window = partial(set_active_window, os_window_id, tab_id)
+
     def bias_increment_for_cell(self, all_windows: WindowList, is_horizontal: bool) -> float:
         self._set_dimensions()
         return self.calculate_bias_increment_for_a_single_cell(all_windows, is_horizontal)

kitty/tabs.py

@@ -184,9 +184,14 @@ def apply_options(self, is_active: bool) -> None:
     def take_over_from(self, other_tab: 'Tab') -> None:
         self.name, self.cwd = other_tab.name, other_tab.cwd
         self.enabled_layouts = list(other_tab.enabled_layouts)
-        if other_tab._current_layout_name:
-            self._set_current_layout(other_tab._current_layout_name)
         self._last_used_layout = other_tab._last_used_layout
+        if clname := other_tab._current_layout_name:
+            cl = other_tab.current_layout
+            other_tab._set_current_layout(clname)
+            cl.set_owner(self.os_window_id, self.id)
+            self.current_layout: Layout = cl
+            self._current_layout_name = clname
+            self.mark_tab_bar_dirty()
         for window in other_tab.windows:
             detach_window(other_tab.os_window_id, other_tab.id, window.id)
         self.windows = other_tab.windows