Add a new `nth_window action that can be used to go to the nth window and also previously active windows, using negative numbers. Similarly, goto_tab` now accepts negative numbers to go to previous windows

Fix #1040

docs/changelog.rst

@@ -15,6 +15,11 @@ Changelog
   be bound to key presses in :file:`kitty.conf`. See
   `https://sw.kovidgoyal.net/kitty/kittens/custom.html`_. (:iss:`870`)
 
+- Add a new ``nth_window`` action that can be used to go to the nth window and
+  also previously active windows, using negative numbers. Similarly,
+  ``goto_tab`` now accepts negative numbers to go to previous windows
+  (:iss:`1040`)
+
 - Fix the ``*_with_cwd`` actions using the cwd of the overlay window rather
   than the underlying window's cwd (:iss:`1045`)
 

docs/index.rst

@@ -160,6 +160,13 @@ windows and move windows around (similar to window movement in vim)::
    map shift+down move_window up
    ...
 
+You can also define a shortcut to switch to the previously active window::
+
+   map ctrl+p nth_window -1
+
+``nth_window`` will focus the nth window for positive numbers and the
+previously active windows for negative numbers.
+
 
 Other keyboard shortcuts
 ----------------------------------

kitty/config.py

@@ -173,6 +173,16 @@ def pipe(func, rest):
     return func, rest
 
 
+@func_with_args('nth_window')
+def nth_window(func, rest):
+    try:
+        num = int(rest)
+    except Exception:
+        log_error('Invalid nth_window number: {}'.format(rest))
+        num = 1
+    return func, [num]
+
+
 def parse_key_action(action):
     parts = action.split(' ', 1)
     func = parts[0]

kitty/config_data.py

@@ -140,7 +140,8 @@ For example::
     'shortcuts.tab': [
             _('Tab management'), '',
             _('''\
-You can also create shortcuts to go to specific tabs, with 1 being the first tab::
+You can also create shortcuts to go to specific tabs, with 1 being the first
+tab, 2 the second tab and -1 being the previously active tab::
 
     map ctrl+alt+1 goto_tab 1
     map ctrl+alt+2 goto_tab 2

kitty/tabs.py

@@ -34,6 +34,7 @@ class Tab:  # {{{
         self.tab_manager_ref = weakref.ref(tab_manager)
         self.os_window_id = tab_manager.os_window_id
         self.id = add_tab(self.os_window_id)
+        self.active_window_history = deque()
         if not self.id:
             raise Exception('No OS window with id {} found, or tab counter has wrapped'.format(self.os_window_id))
         self.opts, self.args = tab_manager.opts, tab_manager.args
@@ -82,6 +83,9 @@ class Tab:  # {{{
     def active_window_idx(self, val):
         try:
             old_active_window = self.windows[self._active_window_idx]
+            self.active_window_history.append(old_active_window.id)
+            if len(self.active_window_history) > 64:
+                self.active_window_history.popleft()
         except Exception:
             old_active_window = None
         self._active_window_idx = max(0, min(val, len(self.windows) - 1))
@@ -255,7 +259,19 @@ class Tab:  # {{{
 
     def nth_window(self, num=0):
         if self.windows:
-            self.active_window_idx = self.current_layout.nth_window(self.windows, num)
+            if num < 0:
+                try:
+                    old_window_id = self.active_window_history[num]
+                except IndexError:
+                    return
+                for idx, w in enumerate(self.windows):
+                    if w.id == old_window_id:
+                        self.active_window_idx = self.current_layout.set_active_window(self.windows, idx)
+                        break
+                else:
+                    return
+            else:
+                self.active_window_idx = self.current_layout.nth_window(self.windows, num)
             self.relayout_borders()
             glfw_post_empty_event()
 
@@ -330,6 +346,7 @@ class TabManager:  # {{{
 
     def __init__(self, os_window_id, opts, args, startup_session):
         self.os_window_id = os_window_id
+        self.last_active_tab_id = None
         self.opts, self.args = opts, args
         self.tabs = []
         self.active_tab_history = deque()
@@ -426,6 +443,15 @@ class TabManager:  # {{{
     def goto_tab(self, tab_num):
         if tab_num < len(self.tabs) and 0 <= tab_num:
             self.set_active_tab_idx(tab_num)
+        elif tab_num < 0:
+            try:
+                old_active_tab_id = self.active_tab_history[tab_num]
+            except IndexError:
+                return
+            for idx, tab in enumerate(self.tabs):
+                if tab.id == old_active_tab_id:
+                    self.set_active_tab_idx(idx)
+                    break
 
     def __iter__(self):
         return iter(self.tabs)