Feat: allow config for showing the main app on tray icon click

[mattdjenkinson]

Summary

Add a Config option to control whether the main window is shown and focused when the tray icon is left-clicked. This allows tray/menu bar apps to show only the context menu on click, without activating the main window.

Ref: #5360

Problem

Currently, handle_tray_icon_event in app.rs unconditionally shows and focuses all windows when the tray icon is left-clicked. This is the default behavior many apps want, but tray apps (menu bar / status bar apps) often want to show only the context menu without activating the main window.

Solution

Add tray_icon_show_window_on_click: bool to Config (default true to preserve current behavior). When set to false, the tray icon left-click will not show or focus the window—only the menu will appear (if configured).

Changes

• config.rs: Added tray_icon_show_window_on_click field (default true) and with_tray_icon_show_window_on_click(bool) setter.
• app.rs: Added the field to App, passed it from config, and updated handle_tray_icon_event to only show/focus windows when the option is true.

Usage

Config::new()
    .with_close_behaviour(WindowCloseBehaviour::WindowHides)
    .with_tray_icon_show_window_on_click(false)
    .with_window(window_builder)