fix(wlr/taskbar): stop forcing tasks onto every output's bar

hide_if_duplicate() unconditionally re-ran handle_output_enter() with
the bar's own wl_output for every non-squashed task, so any app_id or
title event made the task visible on all bars and "all-outputs": false
was effectively ignored. The un-squash path in handle_closed() showed
the replacement task unconditionally, with the same effect.

Track whether the toplevel is actually on the bar's output from the
protocol's output_enter/output_leave events, split the button
show/hide logic out of the protocol handlers, and gate every synthetic
re-show on all-outputs or the tracked output membership.

Fixes #5178

include/modules/wlr/taskbar.hpp

@@ -71,6 +71,10 @@ class Task {
   bool button_visible_ = false;
   bool ignored_ = false;
   bool squashed_ = false;
+  /* Whether the toplevel is on this bar's output, per the protocol's
+   * output_enter/output_leave events */
+  bool on_bar_output_ = false;
+  bool size_allocate_connected_ = false;
 
   bool with_icon_ = false;
   bool with_name_ = false;
@@ -96,6 +100,8 @@ class Task {
   void on_button_size_allocated(Gtk::Allocation& alloc);
   void hide_if_ignored();
   void hide_if_duplicate();
+  void show_button();
+  void hide_button();
 
  public:
   /* Getter functions */

src/modules/wlr/taskbar.cpp

@@ -278,25 +278,18 @@ void Task::hide_if_duplicate() {
   // Squashes if the app is in the squash list and more than 1 instance is open
   if (contains_app && (tbar_->task_id_count(app_id_) > 1 || tbar_->task_title_count(title_) > 1)) {
     squashed_ = true;
-    if (button_visible_) {
-      auto output = gdk_wayland_monitor_get_wl_output(bar_.output->monitor->gobj());
-      handle_output_leave(output);
-    }
+    hide_button();
   }
 
-  if (!squashed_ && !ignored_) {
-    auto output = gdk_wayland_monitor_get_wl_output(bar_.output->monitor->gobj());
-    handle_output_enter(output);
+  if (!squashed_ && !ignored_ && (tbar_->all_outputs() || on_bar_output_)) {
+    show_button();
   }
 }
 
 void Task::hide_if_ignored() {
   if (tbar_->ignore_list().count(app_id_) || tbar_->ignore_list().count(title_)) {
     ignored_ = true;
-    if (button_visible_) {
-      auto output = gdk_wayland_monitor_get_wl_output(bar_.output->monitor->gobj());
-      handle_output_leave(output);
-    }
+    hide_button();
   }
 
   if (!ignored_ && !squashed_) {
@@ -353,6 +346,12 @@ void Task::on_button_size_allocated(Gtk::Allocation& alloc) {
 }
 
 void Task::handle_output_enter(struct wl_output* output) {
+  spdlog::debug("{} entered output {}", repr(), (void*)output);
+
+  if (tbar_->show_output(output)) {
+    on_bar_output_ = true;
+  }
+
   if (ignored_) {
     spdlog::debug("{} is ignored", repr());
     return;
@@ -362,12 +361,34 @@ void Task::handle_output_enter(struct wl_output* output) {
     return;
   }
 
-  spdlog::debug("{} entered output {}", repr(), (void*)output);
+  if (tbar_->all_outputs() || on_bar_output_) {
+    /* The task entered the output of the current bar, make the button visible */
+    show_button();
+  }
+}
 
-  if (!button_visible_ && (tbar_->all_outputs() || tbar_->show_output(output))) {
-    /* The task entered the output of the current bar make the button visible */
+void Task::handle_output_leave(struct wl_output* output) {
+  spdlog::debug("{} left output {}", repr(), (void*)output);
+
+  if (tbar_->show_output(output)) {
+    on_bar_output_ = false;
+  }
+
+  if (!tbar_->all_outputs() && !on_bar_output_) {
+    /* The task left the output of the current bar, make the button invisible */
+    hide_button();
+  }
+}
+
+void Task::show_button() {
+  if (button_visible_) {
+    return;
+  }
+  if (!size_allocate_connected_) {
     button.signal_size_allocate().connect_notify(
         sigc::mem_fun(this, &Task::on_button_size_allocated));
+    size_allocate_connected_ = true;
+  }
   tbar_->add_button(button);
   if (!config_["active-only"].asBool() || active()) {
     button.show();
@@ -375,20 +396,17 @@ void Task::handle_output_enter(struct wl_output* output) {
   button_visible_ = true;
   spdlog::debug("{} now visible on {}", repr(), bar_.output->name);
   tbar_->update_bar_css_classes();
-  }
 }
 
-void Task::handle_output_leave(struct wl_output* output) {
-  spdlog::debug("{} left output {}", repr(), (void*)output);
-
-  if (button_visible_ && !tbar_->all_outputs() && tbar_->show_output(output)) {
-    /* The task left the output of the current bar, make the button invisible */
+void Task::hide_button() {
+  if (!button_visible_) {
+    return;
+  }
   tbar_->remove_button(button);
   button.hide();
   button_visible_ = false;
   spdlog::debug("{} now invisible on {}", repr(), bar_.output->name);
   tbar_->update_bar_css_classes();
-  }
 }
 
 void Task::handle_state(struct wl_array* state) {
@@ -474,9 +492,9 @@ void Task::handle_closed() {
     if (it != tasks.end() && !(*it).ignored_) {
       Task& task = *it;
       task.squashed_ = false;
-      tbar_->add_button(task.button);
-      task.button.show();
-      task.button_visible_ = true;
+      if (tbar_->all_outputs() || task.on_bar_output_) {
+        task.show_button();
+      }
     }
   }