Free, open-source apps by BiswasHost for a monitor shared between a Mac and a Windows PC:
- Switch the monitor's input in one click or one shortcut — from the Mac or the PC.
- Control the monitor from the Mac — brightness, contrast, sharpness, blue light filter, volume, View Mode and colour temperature — without touching its buttons.
- Share keyboard & mouse both ways — use the Mac's keyboard and trackpad on the PC, or the PC's keyboard and mouse on the Mac, with copy & paste of text between them. Encrypted, paired, local network only. Two Windows PCs can share one keyboard & mouse the same way.
A working alternative to ViewSonic's vDisplay Manager on modern macOS, plus the keyboard & mouse sharing it never had. 100% open-source.
Available for:
| Platform | Status |
|---|---|
| 🍎 macOS | ✅ Stable — native menu-bar app (Apple Silicon, macOS 14+) |
| 🪟 Windows | ✅ Stable — tray app with the same window, 0.2 MB (Windows 10 / 11) — input switching, monitor controls, keyboard & mouse sharing |
🟢 Runs the author's daily setup — one ViewSonic XG2409A shared between a MacBook Pro and a Windows PC.
One monitor, two computers: a MacBook on HDMI and a Windows PC on DisplayPort. Switching between them meant reaching behind the monitor for the joystick, opening the on-screen menu and stepping through Input Select every single time.
ViewSonic's own vDisplay Manager should do this, but on current macOS it crashes the moment it starts — inside its "AI presence sensor" module, before any window appears — and its supported-model list doesn't even include gaming monitors like the XG series.
So BHDisplay talks to the monitor directly, using the same DDC/CI commands the monitor's own menu uses. No drivers, no background services, no account — just a menu-bar icon.
- Share one monitor between your Mac and a PC/console — flip between them with ⌃⌥⌘S from anywhere, even while the monitor is showing the other computer.
- Stop digging through the monitor's menu — brightness, contrast, blue light filter and volume are sliders on your screen.
- Knows which port is your Mac — plug the Mac into HDMI 1 or HDMI 2; BHDisplay works it out by itself and labels it This Mac.
- Tells you why a switch "didn't work" — if the other computer is asleep, the monitor's Auto Detect jumps back to the Mac. BHDisplay notices, explains it, and gives you the Auto Detect switch to keep the monitor where you put it.
- One keyboard & mouse for both computers — whichever keyboard and mouse is nearest your hand works on either computer: move the pointer across the screen edge and keep typing.
- No phantom screens, on either computer — while the monitor shows the PC, the Mac turns its output to it off, so the Mac behaves like a plain MacBook; while it shows the Mac, a PC with another screen does the same. Switching back turns it on first, so the monitor never sees an empty input.
- Logs when you need them — Keep a Log / Check Log in the menu of both apps.
- One-click input switching — DisplayPort · HDMI 1 · HDMI 2, from the window or the menu bar.
- Global shortcuts — ⌃⌥⌘S Mac ⇄ other computer · ⌃⌥⌘1 / 2 / 3 DisplayPort / HDMI 1 / HDMI 2. (No Accessibility permission needed.)
- Display Control — brightness, contrast, sharpness, blue light filter, volume + mute.
- View Mode and Color Temperature presets (incl. User Color R/G/B gains).
- Auto Detect on/off — the monitor's own input auto-scan, from the app.
- Monitor information — model, serial, firmware, native resolution, which port the Mac uses.
- Honest controls — values are read back from the monitor, so a setting the monitor locked (e.g. Blue Light Filter in FPS Game mode) snaps back and says so instead of lying.
- Menu-bar resident — a Dock icon only while the settings window is open; Launch at Login from the menu.
- Command line —
BHDisplay --get,BHDisplay --input hdmi1, handy for scripts and Shortcuts.
Each keyboard and mouse works on its own computer and moves to the other only when you push the pointer past the screen edge — whatever the monitor is showing. Moving the mouse never switches the monitor; that stays a menu or shortcut action.
- Monitor shows Windows: the Mac's pointer moves from the MacBook screen onto the monitor → you're on Windows. Push the Windows mouse past the edge facing the MacBook → it's on the Mac.
- Monitor shows the Mac: push the Windows mouse past the far edge of the monitor → it controls the Mac. (The Mac's own pointer doesn't cross into Windows then — you couldn't see it.)
- Both at once — the mouse you moved last wins; neither side ever goes dead.
- Copy & paste text between the computers (password-manager items are never sent).
- ⌘ on the Mac = Ctrl on Windows (optional), adjustable mouse and scroll speed, Caps Lock and key repeat carried across.
- Take your keyboard back any time: ⌃⌥⌘Esc on the Mac, Ctrl+Alt+Win+Esc on Windows. Locking Windows or quitting either app also hands everything back.
Pair once (about 30 seconds):
- Install BHDisplay on both computers (see Download & Install). On the Mac, open BHDisplay and turn on Keyboard & Mouse — macOS asks for the Accessibility permission, which sharing needs (it reads and types keys). On Windows it is on by default (tray icon).
- On the PC: tray icon → Pair a new computer… — it now accepts a pairing for 2 minutes.
- On the Mac: Keyboard & Mouse card → Pair… next to your PC.
- Both screens show the same 6-digit code. Check they match, then click Pair on both.
From then on they reconnect by themselves. Nothing can pair without someone choosing Pair a new computer… on that computer first.
Connection lost (a computer turned off, asleep, a cable or Wi-Fi gone)? After 10 seconds both computers go back to normal, exactly as if they had never been connected — every screen on, each keyboard and mouse at home. When the other computer comes back, they reconnect and pick up the setup by themselves.
The same Windows app shares a keyboard & mouse between two Windows PCs (e.g. two laptops side by side). Install it on both and pair them as above (Pair a new computer… on one, Pair with… on the other). Then open the window on each and choose "The other computer is on my left / right" in the Keyboard & Mouse card, so the pointer crosses at the right edge. Each PC keeps its own monitors — they never switch or turn off each other's screens.
| Shortcut | Mac | Windows |
|---|---|---|
| Monitor: Mac ⇄ other computer | ⌃⌥⌘S | Ctrl+Alt+Win+S |
| Monitor: DisplayPort / HDMI 1 / HDMI 2 | ⌃⌥⌘1 / 2 / 3 | Ctrl+Alt+Win+1 / 2 / 3 |
| Take this computer's keyboard & mouse back | ⌃⌥⌘Esc | Ctrl+Alt+Win+Esc |
- Mac: Apple Silicon (M1 or newer), macOS 14 Sonoma or later.
- Monitor: built and tested on the ViewSonic XG2409A. Brightness, contrast, volume and the other standard controls use standard DDC/CI codes and should work on most ViewSonic monitors. Input codes and View Mode names are model-specific — on other models a port may be labelled differently. Reports from other models are welcome in Issues.
- Turn on DDC/CI on the monitor: Setup Menu ▸ DDC/CI ▸ On.
- Cable matters. Use the Mac's HDMI port or a USB-C to DisplayPort cable. Many USB-C to HDMI adapters pass the picture but block DDC/CI — the app then shows "Monitor refused DDC" and can't switch anything. That is the adapter, not the app.
Asked often, so here it is — the monitor and cable BHDisplay is built and tested with:
| What | Product | Buy |
|---|---|---|
| 🖥️ Monitor | ViewSonic XG2409A — 24″ FHD gaming monitor (DisplayPort + 2× HDMI) | Ryans Computers |
| 🔌 Cable (Mac) | ONTEN OTN-8318 — HDMI to HDMI, 1.5 m — MacBook's HDMI port → monitor | Ryans Computers |
The other computer (e.g. a Windows PC) goes into the monitor's DisplayPort with a normal DisplayPort cable. Not sponsored — just what we use.
Grab the latest build from the Releases page.
Download BHDisplay-x.x.x.pkg (installer) or .dmg (drag to Applications).
.pkg(recommended):- Double-click
BHDisplay-x.x.x.pkg. macOS says it can't verify the developer and offers Move to Trash — click Done instead (don't trash it). - Open System Settings → Privacy & Security, scroll down to "BHDisplay-x.x.x.pkg was blocked…" → Open Anyway → confirm with Touch ID / password.
- The installer opens — click through it. When it finishes, BHDisplay starts by itself
(menu-bar icon), with no second warning — apps installed by the
.pkgaren't flagged.
- Double-click
.dmg: drag BHDisplay to Applications and open it. macOS shows the same warning for the app itself → click Done → System Settings → Privacy & Security → "BHDisplay was blocked…" → Open Anyway → Open.
The "damaged"/"can't be checked" message is just the download-quarantine flag on an un-notarized app — nothing is actually wrong.
Download BHDisplay-x.x.x-windows.exe (about 0.2 MB — it uses the .NET Framework that is
already part of Windows, so there is nothing else to install).
- Double-click it. Windows SmartScreen may say "Windows protected your PC" (the app isn't code-signed — that needs a paid certificate): click More info → Run anyway.
- It installs itself for your user (no admin password): into your Programs folder, with a Start menu entry, and it starts with Windows. You can delete the downloaded file.
- BHDisplay lives in the system tray (click ^ next to the clock if you don't see it). Click the icon for the BHDisplay window — the same controls as on the Mac: inputs, brightness, contrast, sharpness, blue light filter, volume, View Mode, colour temperature, monitor information and keyboard & mouse sharing. Right-click for the quick menu. If Windows asks whether BHDisplay may use the network, allow Private networks.
- More than one screen on the PC? Pick a monitor at the top of the window to adjust that one (Identify shows which is which), and tick "This is the monitor connected to the Mac" on the one your Mac shares — the shortcuts and keyboard sharing always use that monitor. Once ticked, while that monitor shows the Mac, Windows turns its output to it off (and makes your other screen the main display), so apps never open on a screen you can't see. Switching back to the PC turns it on again first and gives the main display back — your arrangement returns exactly as it was.
Update: run the newer download — it replaces the installed copy and keeps your pairing.
Remove: Settings ▸ Apps ▸ BHDisplay ▸ Uninstall.
Self-test: BHDisplay.exe --selftest checks the encryption on that PC without changing anything.
- On the monitor: Setup Menu ▸ DDC/CI ▸ On.
- Open BHDisplay — the window shows your monitor, with your Mac's port marked This Mac.
- Click an input, or press ⌃⌥⌘S to flip to the other computer and back.
- Close the window — BHDisplay keeps running in the menu bar: click its icon to open the window again, right-click for the menu (tick Launch at Login there).
- Optional: install BHDisplay on the PC and pair them (see Keyboard & mouse sharing) — then Ctrl+Alt+Win+S on the PC switches the monitor too, and either keyboard works on both.
If a switch bounces straight back to the Mac, the other computer is asleep (no picture), and the monitor's Auto Detect returned to an input that has one. Wake that computer, or turn Auto Detect off in BHDisplay.
- No internet access — no telemetry, no update pings, no accounts. Monitor control talks only to the monitor, over the display cable.
- Keyboard & mouse sharing stays on your local network and is off on the Mac until you turn it on. Every connection is encrypted (AES-256-GCM, fresh keys per session) and authenticated with each computer's own key; only a paired computer can type or click, and pairing needs a person to start it on that computer and confirm a 6-digit code on both screens (the code can't be forced to match by someone in between). The Mac never accepts or makes a sharing connection on its own addresses. Password-manager clipboard items are never sent.
- No admin rights, no helper tools, no kernel extensions. Sharing needs the Mac's Accessibility permission (to read and type keys); monitor control needs nothing.
- Replies from the monitor are validated (address, length and checksum) before use; saved preferences are checked against the monitor's real inputs, so a corrupt value can't crash the app or send a wrong command.
- Factory reset asks for confirmation, names the monitor, and is only enabled once the monitor has been identified through the same channel the command goes to.
- Raw diagnostic writes on the command line need an explicit
--unsafe, and reset/power codes an additional--really.
See SECURITY.md to report a problem.
Needs Xcode (or the Command Line Tools) — no Xcode project, no dependencies.
./build.sh # → build.noindex/BHDisplay.app
./build.sh --install # build and install to /Applications
./make-dist.sh # → dist/BHDisplay-<ver>.dmg + .pkgThe Windows app builds on the Mac too, with the .NET SDK — no Windows needed:
cd windows/BHDisplayWin && dotnet publish -c Release -o ../dist # → windows/dist/BHDisplay.exeTests: tests/sharecore and tests/sharenet (Swift), tests/gcm (the Windows encryption against
NIST/RFC test vectors and .NET's own), and tests/interop/run.sh (Mac ⇄ Windows and
Windows ⇄ Windows handshake and messages).
Sources/DDC.swift DDC/CI transport over the Apple Silicon display controller (DCP)
Sources/Bridge.h C declarations of the private IOKit I²C functions
Sources/Model.swift monitor state, coalesced writes, read-back checks, port learning
Sources/MonitorInfo.swift what macOS knows about the display (EDID, link type, native mode)
Sources/UI.swift SwiftUI window
Sources/App.swift menu bar, hotkeys, login item, About, command line
Sources/Share*.swift keyboard & mouse sharing: protocol, network, input capture/replay
Sources/DisplayPower.swift turns the Mac's output to the monitor off/on
docs/SHARING-PROTOCOL.md the sharing protocol (both apps implement it)
windows/BHDisplayWin/ BHDisplay for Windows (C#, .NET Framework 4.8, WinForms tray app)
packaging/ installer pages, DMG read-me, pkg preinstall
MIT. See LICENSE. Not affiliated with ViewSonic — see DISCLAIMER.md.
— BiswasHost · https://www.biswashost.com
BHDisplay is free and open-source. If it saved you time, you can buy me a coffee — it genuinely helps me keep building and maintaining free tools like this. 🙏
- bKash/Nagad (Personal · Send Money):
01710378396
ধন্যবাদ! / Thank you!