diff --git a/kitty/borders.py b/kitty/borders.py
index cb5f41675..a07c61322 100644
--- a/kitty/borders.py
+++ b/kitty/borders.py
@@ -4,15 +4,16 @@
 
 from enum import IntFlag
 from itertools import chain
-from typing import List, Optional, Sequence, Tuple
+from typing import Sequence, Tuple
 
 from .fast_data_types import (
     BORDERS_PROGRAM, add_borders_rect, compile_program, init_borders_program,
     os_window_has_background_image
 )
 from .options_stub import Options
+from .typing import LayoutType
 from .utils import load_shaders
-from .typing import WindowType, LayoutType
+from .window_list import WindowGroup, WindowList
 
 
 class BorderColor(IntFlag):
@@ -30,10 +31,12 @@ def horizontal_edge(os_window_id: int, tab_id: int, color: int, height: int, lef
         add_borders_rect(os_window_id, tab_id, left, top, right, top + height, color)
 
 
-def draw_edges(os_window_id: int, tab_id: int, colors: Sequence[int], window: WindowType, borders: bool = False) -> None:
-    geometry = window.geometry
-    pl, pt = window.effective_padding('left'), window.effective_padding('top')
-    pr, pb = window.effective_padding('right'), window.effective_padding('bottom')
+def draw_edges(os_window_id: int, tab_id: int, colors: Sequence[int], wg: WindowGroup, borders: bool = False) -> None:
+    geometry = wg.geometry
+    if geometry is None:
+        return
+    pl, pt = wg.effective_padding('left'), wg.effective_padding('top')
+    pr, pb = wg.effective_padding('right'), wg.effective_padding('bottom')
     left = geometry.left - pl
     top = geometry.top - pt
     lr = geometry.right
@@ -41,7 +44,7 @@ def draw_edges(os_window_id: int, tab_id: int, colors: Sequence[int], window: Wi
     bt = geometry.bottom
     bottom = bt + pb
     if borders:
-        width = window.effective_border()
+        width = wg.effective_border()
         bt = bottom
         lr = right
         left -= width
@@ -69,8 +72,7 @@ class Borders:
 
     def __call__(
         self,
-        windows: List[WindowType],
-        active_window: Optional[WindowType],
+        all_windows: WindowList,
         current_layout: LayoutType,
         extra_blank_rects: Sequence[Tuple[int, int, int, int]],
         draw_window_borders: bool = True,
@@ -82,31 +84,33 @@ class Borders:
                 left, top, right, bottom = br
                 add_borders_rect(self.os_window_id, self.tab_id, left, top, right, bottom, BorderColor.default_bg)
         bw = 0
-        if windows:
-            bw = windows[0].effective_border()
+        groups = tuple(all_windows.iter_all_layoutable_groups(only_visible=True))
+        if groups:
+            bw = groups[0].effective_border()
         draw_borders = bw > 0 and draw_window_borders
         if draw_borders:
-            border_data = current_layout.resolve_borders(windows, active_window)
+            border_data = current_layout.resolve_borders(all_windows)
+        active_group = all_windows.active_group
 
-        for i, w in enumerate(windows):
-            window_bg = w.screen.color_profile.default_bg
+        for i, wg in enumerate(groups):
+            window_bg = wg.default_bg
             window_bg = (window_bg << 8) | BorderColor.window_bg
             if draw_borders:
                 # Draw the border rectangles
-                if w is active_window and self.draw_active_borders:
+                if wg is active_group and self.draw_active_borders:
                     color = BorderColor.active
                 else:
-                    color = BorderColor.bell if w.needs_attention else BorderColor.inactive
+                    color = BorderColor.bell if wg.needs_attention else BorderColor.inactive
                 try:
                     colors = tuple(color if needed else window_bg for needed in next(border_data))
-                    draw_edges(self.os_window_id, self.tab_id, colors, w, borders=True)
+                    draw_edges(self.os_window_id, self.tab_id, colors, wg, borders=True)
                 except StopIteration:
                     pass
             if not has_background_image:
                 # Draw the background rectangles over the padding region
                 colors = window_bg, window_bg, window_bg, window_bg
-                draw_edges(self.os_window_id, self.tab_id, colors, w)
+                draw_edges(self.os_window_id, self.tab_id, colors, wg)
 
         color = BorderColor.inactive
-        for (left, top, right, bottom) in current_layout.window_independent_borders(windows, active_window):
+        for (left, top, right, bottom) in current_layout.window_independent_borders(all_windows):
             add_borders_rect(self.os_window_id, self.tab_id, left, top, right, bottom, color)
diff --git a/kitty/layout/base.py b/kitty/layout/base.py
index b9bd0c84b..1cb3da316 100644
--- a/kitty/layout/base.py
+++ b/kitty/layout/base.py
@@ -4,10 +4,9 @@
 
 from functools import partial
 from itertools import repeat
-from operator import attrgetter
 from typing import (
-    Dict, Generator, Iterable, List, NamedTuple, Optional, Sequence, Tuple,
-    Union, cast
+    Dict, Generator, Iterable, Iterator, List, NamedTuple, Optional, Sequence,
+    Tuple, Union, cast
 )
 
 from kitty.constants import Edges, WindowGeometry
@@ -47,20 +46,13 @@ LayoutDimension = Generator[LayoutData, None, None]
 ListOfWindows = List[WindowType]
 
 
-class InternalNeighborsMap(TypedDict):
+class NeighborsMap(TypedDict):
     left: List[int]
     top: List[int]
     right: List[int]
     bottom: List[int]
 
 
-class NeighborsMap(TypedDict):
-    left: Tuple[int, ...]
-    top: Tuple[int, ...]
-    right: Tuple[int, ...]
-    bottom: Tuple[int, ...]
-
-
 class LayoutGlobalData:
     draw_minimal_borders: bool = True
     draw_active_borders: bool = True
@@ -241,7 +233,10 @@ class Layout:
         return False
 
     def modify_size_of_window(self, all_windows: WindowList, window_id: int, increment: float, is_horizontal: bool = True) -> bool:
-        return self.apply_bias(window_id, increment, all_windows, is_horizontal)
+        idx = all_windows.group_idx_for_window(window_id)
+        if idx is None:
+            return False
+        return self.apply_bias(idx, increment, all_windows, is_horizontal)
 
     def parse_layout_opts(self, layout_opts: Optional[str] = None) -> LayoutOpts:
         data: Dict[str, str] = {}
@@ -264,20 +259,12 @@ class Layout:
     def neighbors(self, all_windows: WindowList) -> NeighborsMap:
         w = all_windows.active_window
         assert w is not None
-        n = self.neighbors_for_window(w, all_windows)
-        id_getter = attrgetter('id')
-        ans: NeighborsMap = {
-            'left': tuple(map(id_getter, n['left'])),
-            'top': tuple(map(id_getter, n['top'])),
-            'right': tuple(map(id_getter, n['right'])),
-            'bottom': tuple(map(id_getter, n['bottom']))
-        }
-        return ans
+        return self.neighbors_for_window(w, all_windows)
 
     def move_window(self, all_windows: WindowList, delta: Union[str, int] = 1) -> bool:
         # delta can be either a number or a string such as 'left', 'top', etc
         # for neighborhood moves
-        if len(all_windows) < 2 or not delta:
+        if all_windows.num_groups < 2 or not delta:
             return False
 
         if isinstance(delta, int):
@@ -291,7 +278,7 @@ class Layout:
         q: List[int] = cast(List[int], neighbors.get(which, []))
         if not q:
             return False
-        return all_windows.move_window_group(to_group_with_window_id=q[0])
+        return all_windows.move_window_group(to_group=q[0])
 
     def add_window(self, all_windows: WindowList, window: WindowType, location: Optional[str] = None, overlay_for: Optional[int] = None) -> None:
         if overlay_for is not None and overlay_for in all_windows:
@@ -349,7 +336,7 @@ class Layout:
 
     def xlayout(
         self,
-        all_windows: WindowList,
+        groups: Iterator[WindowGroup],
         bias: Optional[Sequence[float]] = None,
         start: Optional[int] = None,
         size: Optional[int] = None,
@@ -357,7 +344,7 @@ class Layout:
     ) -> LayoutDimension:
         decoration_pairs = tuple(
             (g.decoration('left'), g.decoration('right')) for i, g in
-            enumerate(all_windows.iter_all_layoutable_groups()) if i >= offset
+            enumerate(groups) if i >= offset
         )
         if start is None:
             start = lgd.central.left
@@ -367,7 +354,7 @@ class Layout:
 
     def ylayout(
         self,
-        all_windows: WindowList,
+        groups: Iterator[WindowGroup],
         bias: Optional[Sequence[float]] = None,
         start: Optional[int] = None,
         size: Optional[int] = None,
@@ -375,7 +362,7 @@ class Layout:
     ) -> LayoutDimension:
         decoration_pairs = tuple(
             (g.decoration('top'), g.decoration('bottom')) for i, g in
-            enumerate(all_windows.iter_all_layoutable_groups()) if i >= offset
+            enumerate(groups) if i >= offset
         )
         if start is None:
             start = lgd.central.top
@@ -383,37 +370,35 @@ class Layout:
             size = lgd.central.height
         return layout_dimension(start, size, lgd.cell_height, decoration_pairs, bias=bias, left_align=lgd.align_top_left)
 
-    def set_window_geometry(self, w: WindowType, idx: int, xl: LayoutData, yl: LayoutData) -> None:
-        wg = window_geometry_from_layouts(xl, yl)
-        w.set_geometry(wg)
-        self.blank_rects.extend(blank_rects_for_window(wg))
+    def set_window_group_geometry(self, wg: WindowGroup, xl: LayoutData, yl: LayoutData) -> WindowGeometry:
+        geom = window_geometry_from_layouts(xl, yl)
+        wg.set_geometry(geom)
+        self.blank_rects.extend(blank_rects_for_window(geom))
+        return geom
 
     def do_layout(self, windows: WindowList) -> None:
         raise NotImplementedError()
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
+    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> NeighborsMap:
         return {'left': [], 'right': [], 'top': [], 'bottom': []}
 
-    def compute_needs_borders_map(self, windows: WindowList, active_window: Optional[WindowType]) -> Dict[int, bool]:
-        return {w.id: ((w is active_window and lgd.draw_active_borders) or w.needs_attention) for w in windows}
+    def compute_needs_borders_map(self, all_windows: WindowList) -> Dict[int, bool]:
+        return all_windows.compute_needs_borders_map(lgd.draw_active_borders)
 
-    def resolve_borders(self, windows: WindowList, active_window: Optional[WindowType]) -> Generator[Borders, None, None]:
+    def resolve_borders(self, windows: WindowList) -> Generator[Borders, None, None]:
         if lgd.draw_minimal_borders:
-            needs_borders_map = self.compute_needs_borders_map(windows, active_window)
-            yield from self.minimal_borders(windows, active_window, needs_borders_map)
+            needs_borders_map = self.compute_needs_borders_map(windows)
+            yield from self.minimal_borders(windows, needs_borders_map)
         else:
-            yield from Layout.minimal_borders(self, windows, active_window, {})
+            yield from Layout.minimal_borders(self, windows, {})
 
     def window_independent_borders(self, windows: WindowList, active_window: Optional[WindowType] = None) -> Generator[Edges, None, None]:
         return
         yield Edges()  # type: ignore
 
-    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 not active_window or lgd.draw_active_borders or w.needs_attention:
-                yield all_borders
-            else:
-                yield no_borders
+    def minimal_borders(self, windows: WindowList, needs_borders_map: Dict[int, bool]) -> Generator[Borders, None, None]:
+        for needs_border in needs_borders_map.values():
+            yield all_borders if needs_border else no_borders
 
     def layout_action(self, action_name: str, args: Sequence[str], all_windows: WindowList) -> Optional[bool]:
         pass
diff --git a/kitty/layout/grid.py b/kitty/layout/grid.py
index 71923b754..89577bcd2 100644
--- a/kitty/layout/grid.py
+++ b/kitty/layout/grid.py
@@ -11,7 +11,7 @@ from kitty.typing import WindowType
 from kitty.window_list import WindowList
 
 from .base import (
-    Borders, InternalNeighborsMap, Layout, LayoutData, LayoutDimension,
+    Borders, NeighborsMap, Layout, LayoutData, LayoutDimension,
     ListOfWindows, all_borders, layout_dimension, lgd, no_borders,
     variable_bias
 )
@@ -213,7 +213,7 @@ class Grid(Layout):
             for border in rows[:-1]:
                 yield border
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
+    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> NeighborsMap:
         n = len(windows)
         if n < 4:
             return neighbors_for_tall_window(1, window, windows)
diff --git a/kitty/layout/splits.py b/kitty/layout/splits.py
index 8d8b32cba..df6b857ef 100644
--- a/kitty/layout/splits.py
+++ b/kitty/layout/splits.py
@@ -11,7 +11,7 @@ from kitty.typing import EdgeLiteral, WindowType
 from kitty.window_list import WindowList
 
 from .base import (
-    Borders, InternalNeighborsMap, Layout, LayoutOpts, all_borders,
+    Borders, NeighborsMap, Layout, LayoutOpts, all_borders,
     blank_rects_for_window, lgd, no_borders, window_geometry_from_layouts
 )
 
@@ -234,7 +234,7 @@ class Pair:
             return parent.modify_size_of_child(which, increment, is_horizontal, layout_object)
         return False
 
-    def neighbors_for_window(self, window_id: int, ans: InternalNeighborsMap, layout_object: 'Splits') -> None:
+    def neighbors_for_window(self, window_id: int, ans: NeighborsMap, layout_object: 'Splits') -> None:
 
         def quadrant(is_horizontal: bool, is_first: bool) -> Tuple[EdgeLiteral, EdgeLiteral]:
             if is_horizontal:
@@ -407,10 +407,10 @@ class Splits(Layout):
             if pair.between_border is not None:
                 yield pair.between_border
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
+    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> NeighborsMap:
         window_id = window.overlay_for or window.id
         pair = self.pairs_root.pair_for_window(window_id)
-        ans: InternalNeighborsMap = {'left': [], 'right': [], 'top': [], 'bottom': []}
+        ans: NeighborsMap = {'left': [], 'right': [], 'top': [], 'bottom': []}
         if pair is not None:
             pair.neighbors_for_window(window_id, ans, self)
         return ans
diff --git a/kitty/layout/tall.py b/kitty/layout/tall.py
index 067fda8f7..6dc3914b9 100644
--- a/kitty/layout/tall.py
+++ b/kitty/layout/tall.py
@@ -3,30 +3,32 @@
 # License: GPLv3 Copyright: 2020, Kovid Goyal <kovid at kovidgoyal.net>
 
 from itertools import repeat
-from typing import Dict, Generator, List, Optional, Tuple
+from typing import Dict, Generator, List, Tuple
 
 from kitty.typing import EdgeLiteral, WindowType
 from kitty.window_list import WindowList
 
 from .base import (
-    Borders, InternalNeighborsMap, Layout, LayoutDimension, LayoutOpts,
-    ListOfWindows, all_borders, lgd, no_borders, normalize_biases,
-    safe_increment_bias, variable_bias
+    Borders, Layout, LayoutDimension, LayoutOpts, NeighborsMap, all_borders,
+    lgd, no_borders, normalize_biases, safe_increment_bias, variable_bias
 )
 
 
-def neighbors_for_tall_window(num_full_size_windows: int, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
-    idx = windows.index(window)
-    prev = None if idx == 0 else windows[idx-1]
-    nxt = None if idx == len(windows) - 1 else windows[idx+1]
-    ans: InternalNeighborsMap = {'left': [prev.id] if prev is not None else [], 'right': [], 'top': [], 'bottom': []}
+def neighbors_for_tall_window(num_full_size_windows: int, window: WindowType, all_windows: WindowList) -> NeighborsMap:
+    wg = all_windows.group_for_window(window)
+    assert wg is not None
+    groups = tuple(all_windows.iter_all_layoutable_groups())
+    idx = groups.index(wg)
+    prev = None if idx == 0 else groups[idx-1]
+    nxt = None if idx == len(groups) - 1 else groups[idx+1]
+    ans: NeighborsMap = {'left': [prev.id] if prev is not None else [], 'right': [], 'top': [], 'bottom': []}
     if idx < num_full_size_windows - 1:
         if nxt is not None:
             ans['right'] = [nxt.id]
     elif idx == num_full_size_windows - 1:
-        ans['right'] = [w.id for w in windows[idx+1:]]
+        ans['right'] = [w.id for w in groups[idx+1:]]
     else:
-        ans['left'] = [windows[num_full_size_windows - 1].id]
+        ans['left'] = [groups[num_full_size_windows - 1].id]
         if idx > num_full_size_windows and prev is not None:
             ans['top'] = [prev.id]
         if nxt is not None:
@@ -72,13 +74,13 @@ class Tall(Layout):
         self.biased_map: Dict[int, float] = {}
         return True
 
-    def variable_layout(self, windows: ListOfWindows, biased_map: Dict[int, float]) -> LayoutDimension:
-        windows = windows[self.num_full_size_windows:]
-        bias = variable_bias(len(windows), biased_map) if len(windows) > 1 else None
-        return self.perp_axis_layout(windows, bias=bias)
+    def variable_layout(self, all_windows: WindowList, biased_map: Dict[int, float]) -> LayoutDimension:
+        num = all_windows.num_groups - self.num_full_size_windows
+        bias = variable_bias(num, biased_map) if num > 1 else None
+        return self.perp_axis_layout(all_windows.iter_all_layoutable_groups(), bias=bias, offset=self.num_full_size_windows)
 
-    def apply_bias(self, idx: int, increment: float, top_level_windows: ListOfWindows, is_horizontal: bool = True) -> bool:
-        num_windows = len(top_level_windows)
+    def apply_bias(self, idx: int, increment: float, all_windows: WindowList, is_horizontal: bool = True) -> bool:
+        num_windows = all_windows.num_groups
         if self.main_is_horizontal == is_horizontal:
             before_main_bias = self.main_bias
             ncols = self.num_full_size_windows + 1
@@ -93,63 +95,67 @@ class Tall(Layout):
         if idx < self.num_full_size_windows or num_of_short_windows < 2:
             return False
         idx -= self.num_full_size_windows
-        before_layout = list(self.variable_layout(top_level_windows, self.biased_map))
+        before_layout = list(self.variable_layout(all_windows, self.biased_map))
         before = self.biased_map.get(idx, 0.)
         candidate = self.biased_map.copy()
         candidate[idx] = after = before + increment
-        if before_layout == list(self.variable_layout(top_level_windows, candidate)):
+        if before_layout == list(self.variable_layout(all_windows, candidate)):
             return False
         self.biased_map = candidate
         return before != after
 
-    def do_layout(self, windows: WindowList, active_window_idx: int) -> None:
-        if len(windows) == 1:
-            self.layout_single_window(windows[0])
+    def do_layout(self, all_windows: WindowList) -> None:
+        num = all_windows.num_groups
+        if num == 1:
+            self.layout_single_window_group(next(all_windows.iter_all_layoutable_groups()))
             return
         is_fat = not self.main_is_horizontal
-        if len(windows) <= self.num_full_size_windows + 1:
-            xlayout = self.main_axis_layout(windows, bias=self.main_bias)
-            for i, (w, xl) in enumerate(zip(windows, xlayout)):
-                yl = next(self.perp_axis_layout([w]))
+        if num <= self.num_full_size_windows + 1:
+            xlayout = self.main_axis_layout(all_windows.iter_all_layoutable_groups(), bias=self.main_bias)
+            for i, (wg, xl) in enumerate(zip(all_windows.iter_all_layoutable_groups(), xlayout)):
+                yl = next(self.perp_axis_layout(iter((wg,))))
                 if is_fat:
                     xl, yl = yl, xl
-                self.set_window_geometry(w, i, xl, yl)
+                self.set_window_group_geometry(wg, xl, yl)
             return
 
-        xlayout = self.main_axis_layout(windows[:self.num_full_size_windows + 1], bias=self.main_bias)
+        main_axis_groups = (gr for i, gr in enumerate(all_windows.iter_all_layoutable_groups()) if i <= self.num_full_size_windows)
+        xlayout = self.main_axis_layout(main_axis_groups, bias=self.main_bias)
         attr: EdgeLiteral = 'bottom' if is_fat else 'right'
         start = lgd.central.top if is_fat else lgd.central.left
-        for i, w in enumerate(windows):
+        for i, wg in enumerate(all_windows.iter_all_layoutable_groups()):
             if i >= self.num_full_size_windows:
                 break
             xl = next(xlayout)
-            yl = next(self.perp_axis_layout([w]))
+            yl = next(self.perp_axis_layout(iter((wg,))))
             if is_fat:
                 xl, yl = yl, xl
-            self.set_window_geometry(w, i, xl, yl)
-            start = getattr(w.geometry, attr) + w.effective_border() + w.effective_margin(attr) + w.effective_padding(attr)
-        ylayout = self.variable_layout(windows, self.biased_map)
+            geom = self.set_window_group_geometry(wg, xl, yl)
+            start = getattr(geom, attr) + wg.decoration(attr)
+        ylayout = self.variable_layout(all_windows, self.biased_map)
         size = (lgd.central.height if is_fat else lgd.central.width) - start
-        for i, w in enumerate(windows):
+        for i, wg in enumerate(all_windows.iter_all_layoutable_groups()):
             if i < self.num_full_size_windows:
                 continue
             yl = next(ylayout)
-            xl = next(self.main_axis_layout([w], start=start, size=size))
+            xl = next(self.main_axis_layout(iter((wg,)), start=start, size=size))
             if is_fat:
                 xl, yl = yl, xl
-            self.set_window_geometry(w, i, xl, yl)
+            self.set_window_group_geometry(wg, xl, yl)
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
+    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> NeighborsMap:
         return neighbors_for_tall_window(self.num_full_size_windows, window, windows)
 
-    def minimal_borders(self, windows: WindowList, active_window: Optional[WindowType], needs_borders_map: Dict[int, bool]) -> Generator[Borders, None, None]:
-        last_i = len(windows) - 1
-        for i, w in enumerate(windows):
-            if needs_borders_map[w.id]:
+    def minimal_borders(self, all_windows: WindowList, needs_borders_map: Dict[int, bool]) -> Generator[Borders, None, None]:
+        num = all_windows.num_groups
+        last_i = num - 1
+        groups = tuple(all_windows.iter_all_layoutable_groups())
+        for i, wg in enumerate(groups):
+            if needs_borders_map[wg.id]:
                 yield all_borders
                 continue
             if i < self.num_full_size_windows:
-                if (last_i == i+1 or i+1 < self.num_full_size_windows) and needs_borders_map[windows[i+1].id]:
+                if (last_i == i+1 or i+1 < self.num_full_size_windows) and needs_borders_map[groups[i+1].id]:
                     yield no_borders
                 else:
                     yield no_borders if i == last_i else self.only_main_border
@@ -157,7 +163,7 @@ class Tall(Layout):
             if i == last_i:
                 yield no_borders
                 break
-            if needs_borders_map[windows[i+1].id]:
+            if needs_borders_map[groups[i+1].id]:
                 yield no_borders
             else:
                 yield self.only_between_border
@@ -172,18 +178,21 @@ class Fat(Tall):
     main_axis_layout = Layout.ylayout
     perp_axis_layout = Layout.xlayout
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
-        idx = windows.index(window)
-        prev = None if idx == 0 else windows[idx-1]
-        nxt = None if idx == len(windows) - 1 else windows[idx+1]
-        ans: InternalNeighborsMap = {'left': [], 'right': [], 'top': [] if prev is None else [prev.id], 'bottom': []}
+    def neighbors_for_window(self, window: WindowType, all_windows: WindowList) -> NeighborsMap:
+        wg = all_windows.group_for_window(window)
+        assert wg is not None
+        groups = tuple(all_windows.iter_all_layoutable_groups())
+        idx = groups.index(wg)
+        prev = None if idx == 0 else groups[idx-1]
+        nxt = None if idx == len(groups) - 1 else groups[idx+1]
+        ans: NeighborsMap = {'left': [], 'right': [], 'top': [] if prev is None else [prev.id], 'bottom': []}
         if idx < self.num_full_size_windows - 1:
             if nxt is not None:
                 ans['bottom'] = [nxt.id]
         elif idx == self.num_full_size_windows - 1:
-            ans['bottom'] = [w.id for w in windows[idx+1:]]
+            ans['bottom'] = [w.id for w in groups[idx+1:]]
         else:
-            ans['top'] = [windows[self.num_full_size_windows - 1].id]
+            ans['top'] = [groups[self.num_full_size_windows - 1].id]
             if idx > self.num_full_size_windows and prev is not None:
                 ans['left'] = [prev.id]
             if nxt is not None:
diff --git a/kitty/layout/vertical.py b/kitty/layout/vertical.py
index 535cfcea7..a4d6d3cba 100644
--- a/kitty/layout/vertical.py
+++ b/kitty/layout/vertical.py
@@ -8,7 +8,7 @@ from kitty.typing import WindowType
 from kitty.window_list import WindowList
 
 from .base import (
-    Borders, InternalNeighborsMap, Layout, LayoutDimension, ListOfWindows,
+    Borders, NeighborsMap, Layout, LayoutDimension, ListOfWindows,
     all_borders, no_borders, variable_bias
 )
 
@@ -72,7 +72,7 @@ class Vertical(Layout):
             else:
                 yield self.only_between_border
 
-    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> InternalNeighborsMap:
+    def neighbors_for_window(self, window: WindowType, windows: WindowList) -> NeighborsMap:
         idx = windows.index(window)
         before = [] if window is windows[0] else [windows[idx-1].id]
         after = [] if window is windows[-1] else [windows[idx+1].id]
diff --git a/kitty/tabs.py b/kitty/tabs.py
index 3bd4d34ae..32c6ac207 100644
--- a/kitty/tabs.py
+++ b/kitty/tabs.py
@@ -188,11 +188,6 @@ class Tab:  # {{{
     def on_bell(self, window: Window) -> None:
         self.mark_tab_bar_dirty()
 
-    def visible_windows(self) -> Generator[Window, None, None]:
-        for w in self.windows:
-            if w.is_visible_in_layout:
-                yield w
-
     def relayout(self) -> None:
         if self.windows:
             self.current_layout(self.windows)
@@ -201,13 +196,12 @@ class Tab:  # {{{
     def relayout_borders(self) -> None:
         tm = self.tab_manager_ref()
         if tm is not None:
-            visible_windows = list(self.visible_windows())
             w = self.active_window
             ly = self.current_layout
             self.borders(
-                windows=visible_windows, active_window=w,
+                all_windows=self.windows,
                 current_layout=ly, extra_blank_rects=tm.blank_rects,
-                draw_window_borders=(ly.needs_window_borders and len(visible_windows) > 1) or ly.must_draw_borders
+                draw_window_borders=(ly.needs_window_borders and self.windows.num_visble_groups > 1) or ly.must_draw_borders
             )
             if w is not None:
                 w.change_titlebar_color()
@@ -420,9 +414,9 @@ class Tab:  # {{{
         neighbors = self.current_layout.neighbors(self.windows)
         candidates = cast(Optional[Tuple[int, ...]], neighbors.get(which))
         if candidates:
-            self.windows.set_active_window_group_for(candidates[0])
+            self.windows.set_active_group(candidates[0])
 
-    def move_window(self, delta: int = 1) -> None:
+    def move_window(self, delta: Union[str, int] = 1) -> None:
         if self.current_layout.move_window(self.windows, delta):
             self.relayout()
 
diff --git a/kitty/window_list.py b/kitty/window_list.py
index ad4aef63c..76638b609 100644
--- a/kitty/window_list.py
+++ b/kitty/window_list.py
@@ -44,6 +44,13 @@ class WindowGroup:
                 return True
         return False
 
+    @property
+    def needs_attention(self) -> bool:
+        for w in self.windows:
+            if w.needs_attention:
+                return True
+        return False
+
     @property
     def base_window_id(self) -> int:
         return self.windows[0].id if self.windows else 0
@@ -71,10 +78,39 @@ class WindowGroup:
         w = self.windows[0]
         return w.effective_margin(which, is_single_window=is_single_window) + w.effective_border() * border_mult + w.effective_padding(which)
 
+    def effective_padding(self, which: EdgeLiteral) -> int:
+        if not self.windows:
+            return 0
+        w = self.windows[0]
+        return w.effective_padding(which)
+
+    def effective_border(self) -> int:
+        if not self.windows:
+            return 0
+        w = self.windows[0]
+        return w.effective_border()
+
     def set_geometry(self, geom: WindowGeometry) -> None:
         for w in self.windows:
             w.set_geometry(geom)
 
+    @property
+    def default_bg(self) -> int:
+        if self.windows:
+            return self.windows[-1].screen.color_profile.default_bg
+        return 0
+
+    @property
+    def geometry(self) -> Optional[WindowGeometry]:
+        if self.windows:
+            return self.windows[-1].geometry
+
+    @property
+    def is_visible_in_layout(self) -> bool:
+        if not self.windows:
+            return False
+        return self.windows[-1].is_visible_in_layout
+
 
 class WindowList:
 
@@ -149,6 +185,11 @@ class WindowList:
                 changed = True
         return changed
 
+    def set_active_group(self, group_id: int) -> bool:
+        for i, gr in enumerate(self.groups):
+            if gr.id == group_id:
+                return self.set_active_group_idx(i)
+
     def change_tab(self, tab: TabType) -> None:
         self.tabref = weakref.ref(tab)
 
@@ -158,8 +199,8 @@ class WindowList:
             for window in g:
                 yield window, window.id == aw
 
-    def iter_all_layoutable_groups(self) -> Iterator[WindowGroup]:
-        return iter(self.groups)
+    def iter_all_layoutable_groups(self, only_visible: bool = False) -> Iterator[WindowGroup]:
+        return iter(g for g in self.groups if g.is_visible_in_layout) if only_visible else iter(self.groups)
 
     def make_previous_group_active(self, which: int = 1, notify: bool = False) -> None:
         which = max(1, which)
@@ -186,6 +227,12 @@ class WindowList:
             if q in g:
                 return g
 
+    def group_idx_for_window(self, x: WindowOrId) -> Optional[int]:
+        q = self.id_map[x] if isinstance(x, int) else x
+        for i, g in enumerate(self.groups):
+            if q in g:
+                return i
+
     def windows_in_group_of(self, x: WindowOrId) -> Iterator[WindowType]:
         g = self.group_for_window(x)
         if g is not None:
@@ -289,16 +336,15 @@ class WindowList:
     def activate_next_window_group(self, delta: int) -> None:
         self.set_active_group_idx(wrap_increment(self.active_group_idx, self.num_groups, delta))
 
-    def move_window_group(self, by: Optional[int] = None, to_group_with_window_id: Optional[int] = None) -> bool:
+    def move_window_group(self, by: Optional[int] = None, to_group: Optional[int] = None) -> bool:
         if self.active_group_idx < 0 or not self.groups:
             return False
         target = -1
         if by is not None:
             target = wrap_increment(self.active_group_idx, self.num_groups, by)
-        if to_group_with_window_id is not None:
-            q = self.id_map[to_group_with_window_id]
+        if to_group is not None:
             for i, group in enumerate(self.groups):
-                if q in group:
+                if group.id == to_group:
                     target = i
                     break
         if target > -1:
@@ -308,3 +354,15 @@ class WindowList:
             self.set_active_group_idx(target)
             return True
         return False
+
+    def compute_needs_borders_map(self, draw_active_borders: bool) -> Dict[int, bool]:
+        ag = self.active_group
+        return {gr.id: ((gr is ag and draw_active_borders) or gr.needs_attention) for gr in self.groups}
+
+    @property
+    def num_visble_groups(self) -> int:
+        ans = 0
+        for gr in self.groups:
+            if gr.is_visible_in_layout:
+                ans += 1
+        return ans