Taskbar Marker

Color-code and label individual taskbar buttons on Windows 11 — so two windows of the same app (two Remote Desktop sessions, two VS Code workspaces, two Chrome profiles) stop looking identical.

No DLL injection, no hooking, no admin rights. It reads the taskbar through UI Automation and paints a click-through overlay on top of it.

Download

Download Leoncl2025.TaskbarMarker-win-Setup.exe from the latest GitHub Release. It installs for the current user, requires no administrator rights, and adds a Start menu shortcut. A self-updating Leoncl2025.TaskbarMarker-win-Portable.zip is also available for users who prefer not to install it. Extract it and run the top-level Taskbar Marker.exe launcher. Both packages bundle the .NET 8 runtime.

Releases before v0.2.0 used a plain portable ZIP. Install or extract v0.2.0 once to move to Velopack; subsequent releases can update themselves.

The executable is currently unsigned, so Windows SmartScreen may show a warning on first run.

Updates

The installed and Velopack portable builds check GitHub Releases shortly after startup. When an update is available, the tray icon shows a notification and its menu offers Install update. The package downloads in the background, is verified against the release feed, and is applied after Taskbar Marker exits; the updated app then restarts automatically.

Use Check for updates... in the tray menu to check manually. Development builds run normally but do not offer updates because they are not inside a Velopack installation or portable package.

How it works

1. Read — every Windows 11 taskbar button is a normal UI Automation Button. AutomationElement.FromHandle(Shell_TrayWnd) gives us each button's name, application id and on-screen rectangle.
2. Match — rules from rules.json are regex-tested against the name and app id.
3. Paint — a layered, always-on-top, WS_EX_TRANSPARENT window draws a colored bar under each matched button plus an optional label chip above the taskbar. Mouse input falls straight through to the real taskbar.

Nothing is injected into explorer.exe, so a Windows update can't crash your shell — worst case the overlay stops appearing.

Build from source

Requires the .NET 8 SDK:

dotnet build -c Release
.\bin\Release\net8.0-windows\TaskbarMarker.exe

The app lives in the system tray.

Writing rules

Right-click the tray icon (or double-click it) and pick Edit rules...:

Add... opens a picker that reads the taskbar live, so a target is chosen rather than typed:

Selecting a button fills in the pattern automatically. When several buttons share the same name — the normal case for two windows of one app while grouping is on — it matches on the app id instead, because that is the only field that tells them apart.

Every add, edit, remove and reorder is written to %LOCALAPPDATA%\TaskbarMarker\rules.json and applied immediately; there is no separate save or reload step. Editing the file by hand also works — it is watched and picked up automatically. Keeping user rules outside the build directory prevents rebuilds and upgrades from deleting personal connection mappings.

TaskbarMarker.exe --edit opens just the editor, which is handy as a shortcut. A background instance notices the saved file on its own.

rules.json

{
  "pollIntervalMs": 750,
  "barHeight": 4,
  "barInset": 6,
  "showLabel": true,
  "labelFontSize": 9,
  "rules": [
    { "matchAppId": "Windows365:11111111", "color": "#E53935", "label": "task1" },
    { "matchAppId": "Windows365:22222222", "color": "#43A047", "label": "investing" },
    { "match": "Visual Studio Code",       "color": "#1E88E5", "label": "code" }
  ]
}

Field	Meaning
match	Case-insensitive regex tested against the button name
matchAppId	Case-insensitive regex tested against the app id
color	Hex color for the bar and the label chip
label	Optional short text; omit it for a color bar only

Both match and matchAppId may be given, in which case both must hit. Rules are evaluated in order and the first hit wins.

Setting	Default	Meaning
pollIntervalMs	750	How often the taskbar is rescanned. Lower feels snappier but costs CPU
barHeight / barInset	4 / 6	Bar thickness and horizontal inset, in px at 100% scaling
showLabel	true	Draw the label chip above the taskbar
labelFontSize	9	Chip font size in points at 100% scaling
includeAllButtons	false	Also allow matching Start / Search / Widgets / tray icons

Sizes scale automatically with each monitor's DPI, derived from the taskbar height.

Inspecting what the taskbar exposes

List taskbar buttons in the tray menu (or TaskbarMarker.exe --list) writes a report of every button UI Automation can see, with its name, app id and rectangle, and flags which rule each one matched. Useful when a rule does not fire:

  * {X=1013,Y=2088,Width=66,Height=72} Remote Desktop - 1 running window  <== MATCH label=task1
    appId: MicrosoftCorporationII.Windows365_8wekyb3d8bbwe!Windows365:11111111-...
  * {X=1079,Y=2088,Width=66,Height=72} Remote Desktop - 1 running window
    appId: MicrosoftCorporationII.Windows365_8wekyb3d8bbwe!Windows365:22222222-...

Notes and limits

• Windows 11 only. Windows 10 exposes its taskbar differently.
• Horizontal taskbars only. Vertical ones are skipped.
• An overlay hides automatically only on the display containing the foreground full-screen app. Markers on other displays remain visible. Overlays also hide while their taskbar is slid away by auto-hide.
• With taskbar grouping on, two windows of the same app share one button. Use matchAppId to tell them apart, or turn grouping off (Settings → Personalization → Taskbar → Taskbar behaviors → Combine taskbar buttons → Never) to get one button per window with the window title as its name.

Layout

Path	Purpose
Program.cs	Entry point, tray icon, poll timer, rules.json watcher
OverlayCoordinator.cs	Scan → match → paint loop, one overlay per taskbar
TaskbarScanner.cs	UI Automation reader
TaskbarOverlay.cs	Layout and GDI+ rendering of bars and chips
OverlayWindow.cs	Layered click-through window
RulesEditorForm.cs	Rule list editor
RuleEditDialog.cs	Single-rule editor with the live taskbar picker
Settings.cs	rules.json model, matching, load/save
Diagnostics.cs	--list report
Native.cs	Win32 interop

License

This project is licensed under the MIT License.