Avoid flicker when starting kittens such as the hints kitten

Fixes #4674

kitty/boss.py

@@ -1427,7 +1427,8 @@ class Boss:
                         'OVERLAID_WINDOW_COLS': str(w.screen.columns),
                     },
                     cwd=w.cwd_of_child,
-                    overlay_for=w.id
+                    overlay_for=w.id,
+                    overlay_behind=end_kitten.has_ready_notification,
                 ),
                 copy_colors_from=w
             )

kitty/layout/base.py

@@ -271,9 +271,12 @@ class Layout:
     def move_window_to_group(self, all_windows: WindowList, group: int) -> bool:
         return all_windows.move_window_group(to_group=group)
 
-    def add_window(self, all_windows: WindowList, window: WindowType, location: Optional[str] = None, overlay_for: Optional[int] = None) -> None:
+    def add_window(
+        self, all_windows: WindowList, window: WindowType, location: Optional[str] = None,
+        overlay_for: Optional[int] = None, put_overlay_behind: bool = False
+    ) -> None:
         if overlay_for is not None and overlay_for in all_windows:
-            all_windows.add_window(window, group_of=overlay_for)
+            all_windows.add_window(window, group_of=overlay_for, head_of_group=put_overlay_behind)
             return
         if location == 'neighbor':
             location = 'after'

kitty/parser.c

@@ -1080,6 +1080,7 @@ dispatch_dcs(Screen *screen, PyObject DUMP_UNUSED *dump_callback) {
                 Py_DECREF(msg); \
             } else PyErr_Clear();
 
+                } else IF_SIMPLE_PREFIX("overlay-ready|", screen_handle_overlay_ready)
                 } else IF_SIMPLE_PREFIX("kitten-result|", screen_handle_kitten_result)
                 } else IF_SIMPLE_PREFIX("print|", screen_handle_print)
                 } else IF_SIMPLE_PREFIX("echo|", screen_handle_echo)

kitty/screen.c

@@ -2134,6 +2134,11 @@ screen_handle_kitten_result(Screen *self, PyObject *msg) {
     CALLBACK("handle_kitten_result", "O", msg);
 }
 
+void
+screen_handle_overlay_ready(Screen *self, PyObject *msg) {
+    CALLBACK("handle_overlay_ready", "O", msg);
+}
+
 void
 screen_request_capabilities(Screen *self, char c, PyObject *q) {
     static char buf[128];

kitty/screen.h

@@ -213,6 +213,7 @@ void screen_handle_echo(Screen *, PyObject *cmd);
 void screen_handle_ssh(Screen *, PyObject *cmd);
 void screen_handle_askpass(Screen *, PyObject *cmd);
 void screen_handle_kitten_result(Screen *, PyObject *cmd);
+void screen_handle_overlay_ready(Screen *, PyObject *cmd);
 void screen_designate_charset(Screen *, uint32_t which, uint32_t as);
 void screen_use_latin1(Screen *, bool);
 void set_title(Screen *self, PyObject*);

kitty/tabs.py

@@ -63,6 +63,7 @@ class SpecialWindowInstance(NamedTuple):
     overlay_for: Optional[int]
     env: Optional[Dict[str, str]]
     watchers: Optional[Watchers]
+    overlay_behind: bool
 
 
 def SpecialWindow(
@@ -73,9 +74,10 @@ def SpecialWindow(
     cwd: Optional[str] = None,
     overlay_for: Optional[int] = None,
     env: Optional[Dict[str, str]] = None,
-    watchers: Optional[Watchers] = None
+    watchers: Optional[Watchers] = None,
+    overlay_behind: bool = False
 ) -> SpecialWindowInstance:
-    return SpecialWindowInstance(cmd, stdin, override_title, cwd_from, cwd, overlay_for, env, watchers)
+    return SpecialWindowInstance(cmd, stdin, override_title, cwd_from, cwd, overlay_for, env, watchers, overlay_behind)
 
 
 def add_active_id_to_history(items: Deque[int], item_id: int, maxlen: int = 64) -> None:
@@ -403,8 +405,8 @@ class Tab:  # {{{
         ans.fork()
         return ans
 
-    def _add_window(self, window: Window, location: Optional[str] = None, overlay_for: Optional[int] = None) -> None:
-        self.current_layout.add_window(self.windows, window, location, overlay_for)
+    def _add_window(self, window: Window, location: Optional[str] = None, overlay_for: Optional[int] = None, overlay_behind: bool = False) -> None:
+        self.current_layout.add_window(self.windows, window, location, overlay_for, put_overlay_behind=overlay_behind)
         self.mark_tab_bar_dirty()
         self.relayout()
 
@@ -422,7 +424,8 @@ class Tab:  # {{{
         copy_colors_from: Optional[Window] = None,
         allow_remote_control: bool = False,
         marker: Optional[str] = None,
-        watchers: Optional[Watchers] = None
+        watchers: Optional[Watchers] = None,
+        overlay_behind: bool = False
     ) -> Window:
         child = self.launch_child(
             use_shell=use_shell, cmd=cmd, stdin=stdin, cwd_from=cwd_from, cwd=cwd, env=env, allow_remote_control=allow_remote_control)
@@ -432,7 +435,7 @@ class Tab:  # {{{
         )
         # Must add child before laying out so that resize_pty succeeds
         get_boss().add_child(window)
-        self._add_window(window, location=location, overlay_for=overlay_for)
+        self._add_window(window, location=location, overlay_for=overlay_for, overlay_behind=overlay_behind)
         if marker:
             try:
                 window.set_marker(marker)
@@ -453,7 +456,7 @@ class Tab:  # {{{
             override_title=special_window.override_title,
             cwd_from=special_window.cwd_from, cwd=special_window.cwd, overlay_for=special_window.overlay_for,
             env=special_window.env, location=location, copy_colors_from=copy_colors_from,
-            allow_remote_control=allow_remote_control, watchers=special_window.watchers
+            allow_remote_control=allow_remote_control, watchers=special_window.watchers, overlay_behind=special_window.overlay_behind
         )
 
     @ac('win', 'Close all windows in the tab other than the currently active window')
@@ -464,6 +467,9 @@ class Tab:  # {{{
                 if window is not active_window:
                     self.remove_window(window)
 
+    def move_window_to_top_of_group(self, window: Window) -> bool:
+        return self.windows.move_window_to_top_of_group(window)
+
     def remove_window(self, window: Window, destroy: bool = True) -> None:
         self.windows.remove_window(window)
         if destroy:

kitty/window.py

@@ -940,6 +940,13 @@ class Window:
         import base64
         self.kitten_result: Dict[str, Any] = json.loads(base64.b85decode(msg))
 
+    def handle_overlay_ready(self, msg: str) -> None:
+        boss = get_boss()
+        tab = boss.tab_for_window(self)
+        if tab is None:
+            return
+        tab.move_window_to_top_of_group(self)
+
     def handle_remote_askpass(self, msg: str) -> None:
         from .shm import SharedMemory
         with SharedMemory(name=msg, readonly=True) as shm:

kitty/window_list.py

@@ -61,8 +61,23 @@ class WindowGroup:
     def active_window_id(self) -> int:
         return self.windows[-1].id if self.windows else 0
 
-    def add_window(self, window: WindowType) -> None:
+    def add_window(self, window: WindowType, head_of_group: bool = False) -> None:
+        if head_of_group:
+            self.windows.insert(0, window)
+        else:
+            self.windows.append(window)
+
+    def move_window_to_top_of_group(self, window: WindowType) -> bool:
+        id
+        try:
+            idx = self.windows.index(window)
+        except ValueError:
+            return False
+        if idx == len(self.windows) - 1:
+            return False
+        del self.windows[idx]
         self.windows.append(window)
+        return True
 
     def remove_window(self, window: WindowType) -> None:
         with suppress(ValueError):
@@ -252,6 +267,19 @@ class WindowList:
                 return i
         return None
 
+    def move_window_to_top_of_group(self, window: WindowType) -> bool:
+        g = self.group_for_window(window)
+        if g is None:
+            return False
+        before = self.active_window
+        if not g.move_window_to_top_of_group(window):
+            return False
+        after = self.active_window
+        changed = before is not after
+        if changed:
+            self.notify_on_active_window_change(before, after)
+        return changed
+
     def windows_in_group_of(self, x: WindowOrId) -> Iterator[WindowType]:
         g = self.group_for_window(x)
         if g is not None:
@@ -292,7 +320,8 @@ class WindowList:
         group_of: Optional[WindowOrId] = None,
         next_to: Optional[WindowOrId] = None,
         before: bool = False,
-        make_active: bool = True
+        make_active: bool = True,
+        head_of_group: bool = False,
     ) -> WindowGroup:
         self.all_windows.append(window)
         self.id_map[window.id] = window
@@ -318,7 +347,7 @@ class WindowList:
                 self.groups.append(target_group)
 
         old_active_window = self.active_window
-        target_group.add_window(window)
+        target_group.add_window(window, head_of_group=head_of_group)
         if make_active:
             for i, g in enumerate(self.groups):
                 if g is target_group: