WindowsHotSpot

Hot corners and window interactions for Windows. Move your mouse to a configured screen corner to trigger an action, drag any window without grabbing the title bar, resize windows with the scroll wheel, pin windows always-on-top, or adjust window transparency — all with a single Ctrl+Alt modifier.

Features

• Hot corners — configurable action per corner per monitor: Win+Tab (Task View), Show Desktop, Action Center, custom keystroke, or disabled
• Window drag anywhere — hold Ctrl+Alt and left-click-drag anywhere on a window to move it (no title bar required)
• Scroll resize — hold Ctrl+Alt and scroll to resize the window under the cursor, anchored to the cursor position
• Always-on-top toggle — hold Ctrl+Alt and double-click a window to pin or unpin it on top; tray balloon confirms the action
• Window transparency — hold Ctrl+Alt+Shift and scroll to adjust the transparency of the window under the cursor
• Configurable zone size and dwell delay
• Drag suppression — dragging a window into the corner does not trigger the corner action
• Multi-monitor aware — independent corner config per monitor; works across monitors at different DPI scaling
• System tray icon — no taskbar button
• Settings dialog with immediate effect (no restart required)
• Start with Windows option
• Self-contained executable — no .NET runtime required on target machine
• No-admin installer

Installation

Download WindowsHotSpot-Setup.exe from the releases page and run it.

The installer does not require admin elevation. The app installs to %LocalAppData%\WindowsHotSpot\.

Windows security warnings

Windows and browsers will likely warn you when downloading or running the installer — SmartScreen may say "Windows protected your PC" and browsers may flag it as untrusted. This is expected: the executable is not code-signed (certificates cost money and this is a free project).

If you're not comfortable dismissing those warnings, download the source and build it yourself — instructions are in the Building from source section below.

Usage

The app starts in the system tray. Right-click the tray icon to access:

• Settings — configure corners, zone size, dwell delay, startup behavior, and window drag options
• About — version info
• Quit — exit the application

Hot corners

Move the cursor to a configured corner and hold it there for the dwell delay. The configured action fires.

Window drag anywhere

Hold Left Ctrl + Left Alt, then left-click and drag anywhere on any restored (non-maximized) window to move it. The initiating click is not forwarded to the application — the window just moves.

• The target window is brought to the foreground at the start of the drag (configurable)
• Maximized windows are skipped — the click passes through normally
• Elevated (admin) windows are skipped — UIPI prevents cross-privilege window moves
• AltGr (Right Ctrl + Left Alt) does not trigger drag
• Releasing Ctrl or Alt mid-drag cancels the drag and leaves the window at its current position

Scroll resize

Hold Left Ctrl + Left Alt and scroll the mouse wheel over any restored window to resize it. The window grows or shrinks symmetrically around the cursor position, keeping the cursor at the same relative spot in the window.

• Scroll up to grow, scroll down to shrink
• Clamped to the system minimum window size and the screen working area (taskbar excluded)
• AltGr and maximized/elevated windows are skipped (same guards as drag)

Always-on-top toggle

Hold Left Ctrl + Left Alt and double-click any window to toggle its always-on-top state. A tray balloon notification confirms whether the window was pinned or unpinned.

• AltGr and maximized/elevated windows are skipped
• The double-click timing uses the system double-click interval (GetDoubleClickTime)

Window transparency

Hold Left Ctrl + Left Alt + Left Shift and scroll the mouse wheel over any window to adjust its transparency. Scroll down to make the window more transparent; scroll up to restore opacity.

• Alpha is clamped to a minimum of ~10% opacity so windows can never become invisible
• Existing window layering (e.g. color-key windows) is preserved
• AltGr and elevated windows are skipped
• The transparency step size is configurable in Settings

Settings

Setting	Default	Description
Zone size	10 px	Size of the corner detection area
Dwell delay	300 ms	How long the cursor must stay in the corner before triggering
Start with Windows	Off	Launch automatically at login
Bring window to front when dragging starts	On	Raise the target window to the foreground at the start of a drag
Pass through clicks when no window is draggable	Off	When Ctrl+Alt+click lands on a non-draggable surface, pass the click through instead of swallowing it
Scroll resize step	20 px	How many pixels to grow/shrink the window per scroll notch
Transparency step	10 α	How much to adjust window opacity per scroll notch (alpha units, 1–50)

Per-monitor corner configuration is available in Settings — select a monitor, configure its four corners independently, or use "Same on all monitors".

Settings are saved to settings.json next to the executable and take effect immediately on Save.

Building from source

Prerequisites

• .NET 10 SDK
• Inno Setup 6 (for building the installer)

Run from source

cd WindowsHotSpot
dotnet run

Build release installer

.\build.ps1

This will:

1. Read the version from WindowsHotSpot/WindowsHotSpot.csproj
2. Patch installer/WindowsHotSpot.iss with the current version
3. Publish a self-contained single-file executable
4. Compile the Inno Setup installer to dist/WindowsHotSpot-Setup.exe

Releasing a new version

1. Update <Version> in WindowsHotSpot/WindowsHotSpot.csproj
2. Run .\build.ps1
3. Distribute dist/WindowsHotSpot-Setup.exe

The installer AppVersion is patched automatically from the csproj — no manual sync needed.

Project structure

WindowsHotSpot/
├── Native/
│   └── NativeMethods.cs       # P/Invoke: WH_MOUSE_LL, WH_KEYBOARD_LL, SetWindowPos, etc.
├── Core/
│   ├── HookManager.cs         # Global mouse hook (WH_MOUSE_LL) with suppression and wheel/double-click events
│   ├── CornerDetector.cs      # Dwell state machine, drag suppression, multi-monitor
│   ├── CornerRouter.cs        # Per-(monitor, corner) detector pool; rebuilt on settings change
│   ├── WindowDragHandler.cs   # Ctrl+Alt drag: WH_KEYBOARD_LL + SetWindowPos
│   ├── ScrollResizeHandler.cs        # Ctrl+Alt+scroll resize: cursor-anchored, edge-clamped
│   ├── AlwaysOnTopHandler.cs         # Ctrl+Alt double-click: WS_EX_TOPMOST toggle + tray balloon
│   ├── WindowTransparencyHandler.cs  # Ctrl+Alt+Shift+scroll: WS_EX_LAYERED alpha adjustment
│   ├── ActionDispatcher.cs    # Dispatches CornerAction to SendInput
│   └── ActionTrigger.cs       # Win+Tab SendInput helper (used by ActionDispatcher)
├── Config/
│   ├── AppSettings.cs         # Settings model
│   ├── ConfigManager.cs       # JSON persistence, SettingsChanged event
│   └── StartupManager.cs      # HKCU Run registry key
├── UI/
│   ├── SettingsForm.cs        # Settings dialog
│   └── KeyRecorderPanel.cs    # Hotkey recorder
├── HotSpotApplicationContext.cs  # App entry point (tray icon, no taskbar button)
├── Program.cs
├── app.manifest               # Per-Monitor V2 DPI awareness declaration
└── WindowsHotSpot.csproj
installer/
└── WindowsHotSpot.iss         # Inno Setup script (AppVersion patched by build.ps1)
dist/
└── WindowsHotSpot-Setup.exe   # Built installer (not committed)
build.ps1                      # Build script: publish + installer

Technical notes

• Uses WH_MOUSE_LL (low-level global mouse hook) for corner detection and WH_KEYBOARD_LL for Ctrl+Alt modifier tracking — both run on the UI thread via the Windows message loop
• Hook callbacks are kept minimal to avoid Windows silently removing them due to timeout (< 300 ms rule)
• Hook delegates are pinned in class fields to prevent garbage collection
• Coordinates from WH_MOUSE_LL (MSLLHOOKSTRUCT.pt) are in physical pixels; Screen.AllScreens bounds match when Per-Monitor V2 DPI awareness is declared in the manifest
• AppContext.BaseDirectory is used for the settings file path (Assembly.Location returns empty for single-file published executables)
• Window drag uses WindowFromPoint → GetAncestor(GA_ROOT) → elevation check → SetWindowPos(SWP_ASYNCWINDOWPOS) to move windows without blocking the hook callback
• Scroll resize anchors the cursor at its fractional position within the window (fx = (cursorX - left) / width), then re-derives newLeft after resizing so the window grows/shrinks around the cursor; clamped per-edge to Screen.WorkingArea
• Always-on-top double-click detection uses GetDoubleClickTime() and SM_CXDOUBLECLK/SM_CYDOUBLECLK polled live (not cached) so it respects runtime system setting changes
• AltGr protection: AltGr synthesises a fake VK_LCONTROL event with LLKHF_INJECTED set — the keyboard hook skips injected LCtrl events; applies to drag, scroll resize, AOT toggle, and transparency
• Window transparency uses WS_EX_LAYERED + LWA_ALPHA via SetLayeredWindowAttributes; existing layered-window flags (e.g. LWA_COLORKEY) are preserved by OR-ing with the existing flags before writing back; alpha is clamped to 25–255

Known limitations

• Elevated (admin) windows cannot be dragged, resized, or toggled always-on-top — UIPI prevents SetWindowPos from a non-elevated process. Clicks pass through normally.
• When an elevated application is in the foreground, SendInput for corner actions may be blocked by UIPI. Task View is processed by Explorer at medium integrity, so in practice corner actions rarely hit this.
• Multiple simultaneous hot corners are not supported.