ThinkPad Backlight Tray

System-tray application that automatically restores ThinkPad keyboard backlight after lid-close, power, and display events.

Stack

• C# on .NET Framework 4.8.1 (built into Windows 10/11)
• WPF for the Info and About dialog windows
• WinForms for NotifyIcon + ContextMenuStrip
• WMI (System.Management) for event monitoring

Runtime behavior

• Entry point is Program.cs ([STAThread]); calls new App().Run().
• App inherits System.Windows.Application, ShutdownMode = OnExplicitShutdown.
• On startup the saved backlight level is restored immediately.
• Event restore pipeline is EventMonitor.cs → App.RestoreBacklight() → BacklightController.cs.
• Backlight restore only runs on the physical console session (skipped in RDP).
• Backlight is controlled exclusively via the IBMPmDrv kernel driver (\\.\IBMPmDrv) using IOCTLs CTL_CODE(34, 2464/2465, 0, 0) with KBAG/KBAS fallback.
• Fn+Space level changes are detected via HKLM\...\IBMPMSVC\Parameters\Notification and persisted automatically.
• Tray menu and dialogs follow the OS dark / light theme.

Install

Download the MSI installer from the latest GitHub Release and run it — no admin required. The installer places files under %LOCALAPPDATA%\ThinkPad-Backlight-Tray and registers auto-start via HKCU\...\Run. Auto-start can also be toggled from the tray menu ("Run at Startup").

# Silent install
msiexec /i ThinkPad-Backlight-Tray-Setup-vX.Y.Z.msi /quiet

# Install with progress bar
msiexec /i ThinkPad-Backlight-Tray-Setup-vX.Y.Z.msi /passive

A portable zip is also provided for manual use.

Requirements

• Windows 10 1809+ or Windows 11 (x64)
• ThinkPad with keyboard backlight support and the Lenovo power management driver (IBMPmDrv)

Build

# Application
dotnet build -c Release

# MSI installer (requires the WiX v6 dotnet tool)
dotnet tool install --global wix
dotnet build installer\ThinkPad-Backlight-Tray.Installer.wixproj `
    -p:Version=1.0.1 `
    -p:PublishDir=$(Resolve-Path .\publish)

Run

.\bin\Release\net481\ThinkPad-Backlight-Tray.exe

CLI

--off / --dim / --full     Set backlight level and exit
--restore                  Restore backlight level and exit
--restore-to <last|dim|full>
                           Set which level to restore to
--startup-on / --startup-off   Toggle run-at-startup
--info                     Print driver diagnostics and exit
--debug                    Launch tray with live debug logging to a console window
--help                     Show usage

Settings

Registry root: HKEY_CURRENT_USER\Software\ThinkPad-Backlight-Tray

• BacklightLevel (DWORD): 0 Off, 1 Dim, 2 Full
• AutoRestore (DWORD): 1 enabled (default), 0 disabled
• RestoreLevel (DWORD): 0 Last (default), 1 Dim, 2 Full

Versioning & Releases

This project uses Semantic Versioning.

• The single source of truth for the version number is the <Version> property in ThinkPad-Backlight-Tray.csproj.
• All notable changes are recorded in CHANGELOG.md following the Keep a Changelog format.

Release checklist:

1. Update <Version> in ThinkPad-Backlight-Tray.csproj.
2. Add a new section to CHANGELOG.md with the version and date.
3. Commit: git commit -am "Release vX.Y.Z".
4. Tag: git tag vX.Y.Z.
5. Push: git push --follow-tags.

Pushing a v* tag triggers the Release GitHub Action (.github/workflows/release.yml), which builds the project and publishes a portable zip and per-user installer to GitHub Releases.

Key files

• App.cs — WPF Application subclass: lifecycle, NotifyIcon, tray menu, Info dialog, About dialog, restore callbacks
• BacklightController.cs — IBMPmDrv wrapper + retries
• PmDriverBacklightController.cs — IBMPmDrv IOCTL set/get (MLCG/MLCS + KBAG/KBAS fallback)
• EventMonitor.cs — WMI watchers + display polling + Fn+Space watcher
• SessionHelper.cs — physical console session detection
• SettingsManager.cs — registry persistence (backlight level, auto-restore, run-at-startup)
• Program.cs — entry point ([STAThread]) + CLI switch handler
• installer/setup.wxs — WiX v6 MSI installer source
• installer/ThinkPad-Backlight-Tray.Installer.wixproj — WiX MSBuild project (per-user, no admin)

License

MIT