Allow focusing previously active OS windows via nth_os_window

Fixes #7009
Fixes #7008

docs/changelog.rst

@@ -54,6 +54,8 @@ Detailed list of changes
 
 - A new action :ac:`send_key` to simplify mapping key presses to other keys without needing :ac:`send_text`
 
+- Allow focusing previously active OS windows via :ac:`nth_os_window` (:pull:`7009`)
+
 - Wayland: Fix a regression in the previous release that broke copying to clipboard under wl-roots based compositors in some circumstances
   (:iss:`6890`)
 

kitty/boss.py

@@ -94,6 +94,7 @@ from .fast_data_types import (
     is_modifier_key,
     last_focused_os_window_id,
     mark_os_window_for_close,
+    os_window_focus_counters,
     os_window_font_size,
     patch_global_colors,
     redirect_mouse_handling,
@@ -1705,12 +1706,37 @@ class Boss:
                         text = '\n'.join(urls)
                 w.paste_text(text)
 
-    @ac('win', 'Focus the nth OS window')
+    @ac('win', '''
+        Focus the nth OS window if positive or the previously active OS windows if negative. When the number is larger
+        than the number of OS windows focus the last OS window. A value of zero will refocus the currently focused OS window,
+        this is useful if focus is not on any kitty OS window at all, however, it will only work if the window manager
+        allows applications to grab focus. For example::
+
+            # focus the previously active OS window
+            map ctrl+p nth_window -1
+            # focus the first OS window
+            map ctrl+1 nth_window 0
+    ''')
     def nth_os_window(self, num: int = 1) -> None:
-        if self.os_window_map and num > 0:
-            ids = list(self.os_window_map.keys())
+        if not self.os_window_map:
+            return
+        if num == 0:
+            os_window_id = current_focused_os_window_id() or last_focused_os_window_id()
+            focus_os_window(os_window_id, True)
+        elif num > 0:
+            ids = tuple(self.os_window_map.keys())
             os_window_id = ids[min(num, len(ids)) - 1]
             focus_os_window(os_window_id, True)
+        elif num < 0:
+            fc_map = os_window_focus_counters()
+            s = sorted(fc_map.keys(), key=fc_map.__getitem__, reverse=True)
+            if not s:
+                return
+            try:
+                os_window_id = s[num-1]
+            except IndexError:
+                os_window_id = s[0]
+            focus_os_window(os_window_id, True)
 
     @ac('win', 'Close the currently active OS Window')
     def close_os_window(self) -> None:

kitty/fast_data_types.pyi

@@ -1557,3 +1557,4 @@ def base64_decode(src: Union[bytes,str]) -> bytes: ...
 def cocoa_recreate_global_menu() -> None: ...
 def cocoa_clear_global_shortcuts() -> None: ...
 def update_pointer_shape(os_window_id: int) -> None: ...
+def os_window_focus_counters() -> Dict[int, int]: ...

kitty/state.c

@@ -116,7 +116,6 @@ last_focused_os_window_id(void) {
     return ans;
 }
 
-
 static id_type
 current_focused_os_window_id(void) {
     for (size_t i = 0; i < global_state.num_os_windows; i++) {
@@ -1327,10 +1326,25 @@ KKK(set_active_window)
 KII(swap_tabs)
 KK5I(add_borders_rect)
 
+static PyObject*
+os_window_focus_counters(PyObject *self UNUSED, PyObject *args UNUSED) {
+    RAII_PyObject(ans, PyDict_New());
+    for (size_t i = 0; i < global_state.num_os_windows; i++) {
+        OSWindow *w = &global_state.os_windows[i];
+        RAII_PyObject(key, PyLong_FromUnsignedLongLong(w->id));
+        RAII_PyObject(val, PyLong_FromUnsignedLongLong(w->last_focused_counter));
+        if (!key || !val) return NULL;
+        if (PyDict_SetItem(ans, key, val) != 0) return NULL;
+    }
+    Py_INCREF(ans);
+    return ans;
+}
+
 #define M(name, arg_type) {#name, (PyCFunction)name, arg_type, NULL}
 #define MW(name, arg_type) {#name, (PyCFunction)py##name, arg_type, NULL}
 
 static PyMethodDef module_methods[] = {
+    M(os_window_focus_counters, METH_NOARGS),
     MW(update_pointer_shape, METH_VARARGS),
     MW(current_os_window, METH_NOARGS),
     MW(next_window_id, METH_NOARGS),