WinMsg

This is a very basic Windows GUI application that takes a message to display and a timeout as the parameters and does exactly that. The message is displayed in the center of the black full-screen window in large white text, then the app exits automatically.

I wrote it for Sunshine / Moonlight streaming as a companion application when running command-line tools on a host via Moonlight.

The common use case is to control the host PC state (Shut down / Sleep / Hibernate) with the tools like NirCmd.

Instead of the black screen and an error dialog, if the connection is aborted unexpectedly, the user will see the message from this app, then the stream will close gracefully after the app exists.

This project page and documentation below also serve as a guide how to set up sleep/shutdown via Sunshine app shortcuts for Moonlight so that you can manually control your host state directly from a client.

Of course, there are other solutions for that:

• add an Undo command in Sunshine to run a tool that will suspend the PC when the app you stream exists
• configure Windows Power profile to sleep/hibernate/shutdown after N minutes of inactivity
• if streaming from Steam Deck, use MoonDeck/MoonDeck Buddy to control the PC state
• for true nerds, use HomeAssistant with HASS Agent and a WOL switch so that you can control the host PC via voice commands, HA dashboard, CLI and automations

While all the above will work just fine, sometimes you may want to manually force the streaming host to sleep directly from the client. That is where the below guide should help.

Usage

winmsg.exe [<message>] [<timeout>]

The message is the actual message to display, make sure to surround it with double quotes if it contains spaces. Timeout is the time in milliseconds to display the message. The app exits after timeout.

Example:

winmsg.exe "Going to sleep..." 5000

This will show the "Going to sleep..." message in the center of the black screen and exit after 5 seconds (5000ms).

If no parameters are provided, the app will show the empty black screen with no text and exit after 5 seconds.

Sample Sunshine Application configuration to suspend the PC via NirCmd

Click to show the screenshot

Open Applications settings in Sunshine Web UI (https://<sunshine-pc>:47990/apps), click Add New.

Make sure to download and install NirCmd so that it's available in your PATH (or adjust the Detached Command to use the full path to nircmd.exe). This app can do many things, including putting the PC in sleep mode (standby command), shutting down the PC (exitwin shutdown), rebooting (exitwin reboot), and much more.

In this example, we use the following command in the Detached Commands section (to be run in the background):

nircmd.exe cmdwait 20000 standby

cmdwait 20000 waits 20 seconds before forcing the PC to sleep, this allows Moonlight to disconnect properly and Sunshine to run "Undo" commands, if needed. Feel free to use a shorter delay.

As the main Command we use this 'winmsg.exe' tool to display a message and exit after timeout:

winmsg.exe "Sleeping..." 5000

Recommended options:

• Global Prep Commands: Disabled — this allows the command to run faster as the global Do/Undo commands will not run
• Continue streaming if the application exits quickly: Uncheck — the app will quick quickly anyway, we don't want any special handling by Sunshine
• Continue streaming until all app processes exit: Uncheck — also not needed for our case
• Exit Timeout: 0 — for faster exit if forced by the client
• cmdwait value should be greater than winmsg timeout (20000 > 5000 in this example)

If you run the configured Sleep app via Moonlight, it will start the streaming session, run the nircmd.exe in background with the timeout, run winmsg.exe as your main streaming app, you will see the specified message, after 5 seconds the app will exit, Moonlight will close the streaming session and then the PC with Sunshine will go to sleep after ~15 more seconds.

Click for Moonlight Sleep shortcut sample

Compiling

This project can be built on Windows with MinGW/CMake.

Inside mingw64 shell, cd into the project root directory, then:

pacman -S mingw-w64-x86_64-ninja
pacman -S mingw-w64-x86_64-cmake
mkdir build
cd build
cmake ..
cmake --build . --config Release

winmsg.exe file will be in the build directory.

You can also use JetBrains CLion IDE to open this project and build it right away as it already comes with MinGW toolchain and CMake build tool.

Or just download the pre-compiled binary from the Releases page.