Handle display connection loss gracefully instead of crashing

[Copilot]

Waybar crashes when the display connection breaks (e.g., when opening dosbox), showing "Error reading events from display: Broken pipe" before terminating. The GTK main loop doesn't recover from this condition.

Changes

Install GLib log handlers to intercept display errors (src/client.cpp)

• Added gdkLogHandler that detects "Error reading events from display" and "Broken pipe" messages
• Calls gtk_app->quit() for clean shutdown, falls back to std::exit(1) if GTK isn't initialized
• Forwards other log messages to spdlog at appropriate levels
• Installed after gtk_app creation to ensure availability:
  • Gdk/Gtk handlers use G_LOG_LEVEL_MASK
  • Default handler limited to G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL to avoid library interference

Resource cleanup (include/client.hpp, src/client.cpp)

• Store handler IDs as member variables
• Remove handlers in ~Client() destructor via g_log_remove_handler()

void gdkLogHandler(const gchar* log_domain, GLogLevelFlags log_level, 
                   const gchar* message, gpointer user_data) {
  if (message && (strstr(message, "Error reading events from display") != nullptr ||
                  strstr(message, "Broken pipe") != nullptr)) {
    spdlog::error("Display connection lost: {}. Exiting gracefully.", message);
    auto* client = waybar::Client::inst();
    if (client && client->gtk_app) {
      client->gtk_app->quit();
    } else {
      std::exit(1);
    }
    return;
  }
  // Forward other messages to spdlog...
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>waybar crashes when opening dosbox</issue_title>
<issue_description>```
[2025-07-28 11:46:56.606] [info] Using configuration file /home/killertofus/.config/waybar/config.jsonc
[2025-07-28 11:46:56.606] [info] Including resource file: ~/.config/waybar/modules.json
[2025-07-28 11:46:56.607] [info] Using CSS file /home/killertofus/.config/waybar/style.css
[2025-07-28 11:46:56.612] [warning] 'swap-icon-label' must be a bool.
[2025-07-28 11:46:56.613] [warning] No batteries.
[2025-07-28 11:46:56.641] [info] Bar configured (width: 1920, height: 32) for output: DVI-D-1

** (waybar:740594): WARNING **: 11:46:56.644: Status Notifier Item with bus name ':1.5' and object path '/org/ayatana/NotificationItem/nm_applet' is already registered

** (waybar:740594): WARNING **: 11:46:56.661: Status Notifier Item with bus name ':1.5' and object path '/org/ayatana/NotificationItem/nm_applet' is already registered

** (waybar:740594): WARNING **: 11:46:58.018: Status Notifier Item with bus name ':1.5' and object path '/org/ayatana/NotificationItem/nm_applet' is already registered

** (waybar:740594): WARNING **: 11:47:07.193: Status Notifier Item with bus name ':1.5' and object path '/org/ayatana/NotificationItem/nm_applet' is already registered
Gdk-Message: 11:47:25.323: Error reading events from display: Broken pipe

https://github.com/user-attachments/assets/687e98ea-2fc9-4de7-b526-7340d8943641


my config https://github.com/killertofus/awesome/tree/dw-arch/.config/waybar</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes waybar crashes when opening dosbox #4332

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.