Grouped Window List Window Association Enhancements

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Problem

In Cinnamon, the Grouped Window List (GWL) applet relies on Cinnamon.WindowTracker to associate running windows with their corresponding launcher .desktop files. This association frequently fails for applications that:

1. Do not define a StartupWMClass key in their .desktop files.
2. Have casing discrepancies between their X11 WM_CLASS values and their .desktop file names (e.g. Brave-browser vs brave-browser.desktop or GitKraken vs GitKraken.desktop).
3. Are launched via wrapper scripts or subprocess execution models (e.g. Electron apps, Java applications, or multi-process systems), which obscures the mapping process.

When this failure occurs, the window is classified as a transient or generic application. The GWL applet then spawns a duplicate, unpinned icon on the panel rather than nesting/grouping the window under its existing pinned launcher.

Additionally, a potential early-startup race condition existed in onWindowSkipTaskbarChanged where getCurrentWorkspace() could return null before workspaces were fully loaded, causing a fatal JS TypeError (TypeError: currentWorkspace is null) that broke subsequent applet event handling.

Changes Included

1. Pinned Launcher Fallback Matching (_matchWindowToPinnedApp)

Introduced a helper method _matchWindowToPinnedApp(metaWindow) that proactively queries the pinned favorites list to resolve window associations if the standard WindowTracker lookup fails or returns a transient app. It matches a window's WM_CLASS (both class name and instance name) and GTK application ID against:

• Desktop file base names: Case-insensitively matches the base name of the pinned desktop launcher (e.g., gitkraken derived from GitKraken.desktop).
• StartupWMClass Key: Retrieves the StartupWMClass key from the .desktop file metadata (using Gio.AppInfo APIs) and compares it case-insensitively.
• Executable/Command Line: Extracts the executable name/command line specified in the .desktop entry's Exec field to match against the running process's window class.

2. TypeError Null-Check

Added a null-check check for currentWorkspace at the entry point of onWindowSkipTaskbarChanged in applet.js:

    onWindowSkipTaskbarChanged(display, metaWindow) {
        const currentWorkspace = this.getCurrentWorkspace();
        if (!currentWorkspace) {
            return;
        }
        // ...
    }

This safely prevents early-startup crashes when taskbar skip events are fired before the workspace array is fully initialized.

Rationale & Benefits

• Zero-Configuration Grouping: Users no longer need to manually modify system-wide or user-space .desktop entries to add StartupWMClass keys or fix casing to prevent duplicate icons.
• Electron & Wrapper Compatibility: Automatically corrects mapping for popular Electron-based applications (like GitKraken, Slack, VS Code, Discord) and standard applications with wrapper binaries.
• Robust Shell Reliability: Eliminates a known startup-time JS crash, ensuring that window tracker callbacks are consistently registered and handled.