Fix tab activity tracking not working unless there is some other activity in tab bar as well

Fixes #3571

docs/changelog.rst

@@ -18,6 +18,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - macOS: Fix Spotlight search of global menu not working in non-English locales
   (:pull:`3567`)
 
+- Fix tab activity symbol not appearing if no other changes happen in tab bar even when
+  there is activity in a tab (:iss:`3571`)
+
 
 0.20.2 [2021-04-28]
 ----------------------

kitty/boss.py

@@ -768,6 +768,12 @@ def on_focus(self, os_window_id: int, focused: bool) -> None:
                     cocoa_set_menubar_title(w.title or '')
             tm.mark_tab_bar_dirty()
 
+    def on_activity_since_last_focus(self, window: Window) -> None:
+        os_window_id = window.os_window_id
+        tm = self.os_window_map.get(os_window_id)
+        if tm is not None:
+            tm.mark_tab_bar_dirty()
+
     def update_tab_bar_data(self, os_window_id: int) -> None:
         tm = self.os_window_map.get(os_window_id)
         if tm is not None:

kitty/screen.c

@@ -571,6 +571,7 @@ screen_draw(Screen *self, uint32_t och, bool from_input_stream) {
     if (is_ignored_char(och)) return;
     if (!self->has_activity_since_last_focus && !self->has_focus) {
         self->has_activity_since_last_focus = true;
+        CALLBACK("on_activity_since_last_focus", NULL);
     }
     uint32_t ch = och < 256 ? self->g_charset[och] : och;
     bool is_cc = is_combining_char(ch);

kitty/window.py

@@ -612,6 +612,10 @@ def is_active(self) -> bool:
     def has_activity_since_last_focus(self) -> bool:
         return self.screen.has_activity_since_last_focus()
 
+    def on_activity_since_last_focus(self) -> None:
+        if self.opts.tab_activity_symbol:
+            get_boss().on_activity_since_last_focus(self)
+
     def on_bell(self) -> None:
         if self.opts.command_on_bell and self.opts.command_on_bell != ['none']:
             import shlex

kitty_tests/__init__.py

@@ -51,6 +51,9 @@ def clear(self) -> None:
         self.notifications = []
         self.open_urls = []
 
+    def on_activity_since_last_focus(self) -> None:
+        pass
+
 
 def filled_line_buf(ynum=5, xnum=5, cursor=Cursor()):
     ans = LineBuf(ynum, xnum)