feat(MouseWithoutBorders): Prevent Easy Mouse from moving to another machine when an application is running in fullscreen mode.

[dot-tb]

Summary of the Pull Request

This PR adds a new feature to Easy Mouse, it is now possible to toggle a setting that will prevent Easy Mouse to switch away from the host machine when the foreground application is running in full screen mode, requiring the user to first alt tab out of the application before performing the switch, this also comes with a way to allow the switch on specific apps.

PR Checklist

• Closes: Add an option to disable Mouse Without borders while in fullscreen games/applications  #32197
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: [PowerToys]Mouse without borders: Disable Easy mouse when the foreground application is in fullscreen mode - docs MicrosoftDocs/windows-dev-docs#5470

Detailed Description of the Pull Request / Additional comments

This PR changes the way Easy Mouse checks wherever it should move to another machine, after checking that the corresponding setting is enabled and that we are trying to move away from the host machine, it will run a test using native WinAPI methods to get the foreground window and check if it is running in full screen.

If it is, it will then check the name of the executable against a list of ignored app configured by the user, if the executable is found in that list, the switch will be allowed despite the application running in full screen.

These new settings were moved along with the original Easy Mouse toggle to a new "Easy Mouse" setting group to avoid cluttering the Keyboard shortcuts group.

This feature will only work when used from the controller machine, as I didn't find a way to easily check for running application on a remote machine that didn't involved touching the sockets, I felt like such a change would be out of scope for this issue.

Validation Steps Performed

I had a hard time writing tests and didn't achieve anything meaningful enough to be included, I may require some guidance on how to properly write tests for this project.

I tested my changes by running my modified version of MouseWithoutBorders on my machines, which I did for a few days now, It allowed me to catch a few bugs, but it has been running smoothly otherwise.

My changes didn't seemed to have caused any automated tests to fail.

It may require some additional testing for setups including more than two machines.

[dot-tb]

@microsoft-github-policy-service agree

[Copilot]

Pull Request Overview

This PR adds a toggle and exclusion list to prevent Easy Mouse from switching machines when a fullscreen application is active.

• Introduces two new settings: disabling Easy Mouse on fullscreen and a per-app exclusion list.
• Updates ViewModel, UI (XAML), and settings properties to surface the new controls.
• Implements native WinAPI calls to detect fullscreen apps and block switches accordingly.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/settings-ui/Settings.UI/ViewModels/MouseWithoutBordersViewModel.cs	Adds properties to bind fullscreen‐block toggle and exclusion list.
src/settings-ui/Settings.UI/Strings/en-us/Resources.resw	Adds new resource strings for the fullscreen toggle and expander.
src/settings-ui/Settings.UI/SettingsXAML/Views/MouseWithoutBordersPage.xaml	Inserts UI controls (ToggleSwitch, InfoBar, Expander) for the new feature.
src/settings-ui/Settings.UI.Library/MouseWithoutBordersProperties.cs	Defines new properties and default values for the fullscreen settings.
src/modules/MouseWithoutBorders/App/Core/Event.cs	Integrates fullscreen-check logic into mouse‐move event handler.
src/modules/MouseWithoutBorders/App/Class/Setting.cs	Exposes internal getters/setters for the new settings.
src/modules/MouseWithoutBorders/App/Class/NativeMethods.cs	Adds P/Invoke declarations and enums for fullscreen detection.
src/modules/MouseWithoutBorders/App/Class/Common.cs	Implements logic to detect blocked fullscreen apps and overall switch allowance.

Comments suppressed due to low confidence (4)

src/modules/MouseWithoutBorders/App/Core/Common.cs:1620

• This new fullscreen‐blocking logic lacks unit or integration tests. Consider adding tests for various window states and exclusion list behavior.

internal static bool IsEasyMouseSwitchAllowed()

src/settings-ui/Settings.UI/ViewModels/MouseWithoutBordersViewModel.cs:1016

• [nitpick] Property name 'EasyMouseEnabledAndDisableOnFullscreen' is confusing. Consider renaming to something like 'IsEasyMouseBlockingOnFullscreenEnabled' for clarity.

public bool EasyMouseEnabledAndDisableOnFullscreen =>

src/settings-ui/Settings.UI/ViewModels/MouseWithoutBordersViewModel.cs:908

• Assigning an array literal to a HashSet property will not compile. Consider converting the split values into a HashSet, e.g., new HashSet(value.Split('\r')).

Settings.Properties.EasyMouseFullscreenSwitchBlockExcludedApps.Value = value == string.Empty ? [] : [..value.Split('\r')];

src/settings-ui/Settings.UI.Library/MouseWithoutBordersProperties.cs:185

• Initializing a GenericProperty<HashSet> with [] produces a string[] rather than a HashSet. Use new GenericProperty<HashSet>(new HashSet()) instead.

EasyMouseFullscreenSwitchBlockExcludedApps = new GenericProperty<HashSet<string>>([]);

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[dot-tb]

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This wasn't added by my PR.

[vanzue]

Thanks for this, Let's target this pr into 93 release ❤️

[dot-tb]

Thanks for this, Let's target this pr into 93 release ❤️

Should I keep this PR up to date with the main branch ?

[vanzue]

I don't think you have to, let's do once before check in 🙂