External Mode

External mode writes a temporary .rdp file, optionally stages credentials in the Windows credential manager, and launches the Remote Desktop client as a separate process.

Key behaviors:

• The process is tracked with a Windows job object when External.KillProcessOnHostExit is enabled, so the external session is terminated if the host process is killed.
• Temporary credentials are restored or removed after the external client exits.
• Monitor selection can be written through External.SelectedMonitors. This is intentionally external-only because the embedded ActiveX host cannot reliably present arbitrary selected-monitor layouts.
• RemoteApp settings are written as standard .rdp properties when RemoteApp.Enabled is true.
• gateway settings and Connection.UseRedirectionServerName are written as standard .rdp properties for brokered RDS / AVD-style connections.
• when both target-server and RD Gateway credentials are configured, the credential manager staging path now handles them as two independent temporary credentials with separate restore/remove behavior.
• RdpControl.ActivateExternalSessionWindow() can be used as a best-effort helper to bring the external launcher window back to the foreground.
• RdpControl.ExternalSessionWindowChanged reports when the launcher window is discovered or lost, and RdpControl.ExternalSessionWindowHandle exposes the last known handle.
• Additional .rdp settings can be appended through External.AdditionalRdpSettings.
• External.MsRdpExSearchPaths can be used to probe app-local directories or full file paths for mstscex.exe before the built-in well-known installation folders.
• when no configured or installed mstscex.exe is found, the library can extract bundled x64 or arm64 copies of both mstscex.exe and MsRdpEx.dll into a per-user cache folder as a fallback.
• the bundled fallback cache location is %LocalAppData%\RoyalApps.Community.Rdp.WinForms\MsRdpEx\<version>\<rid>.
• only win-x64 and win-arm64 are bundled. x86 still requires an explicit path, search path, or installed MsRdpEx launcher.
• External.MsRdpEx provides typed hook-specific settings for KDCProxyURL, UserSpecifiedServerName, EnableMouseJiggler, MouseJigglerInterval, and MouseJigglerMethod.
• shared settings such as Connection.DisableUdpTransport, Input.AllowBackgroundInput, Input.RelativeMouseMode, Performance.EnableHardwareMode, and the low-level security flags are also emitted in MsRdpEx form when hooks are enabled.
• raw MsRdpEx-specific settings can still be appended through External.AdditionalMsRdpExSettings, and those entries are emitted after the typed mapping so they can override it when necessary.

Security behavior:

• Security.RemoteCredentialGuard implies DisableCredentialsDelegation and RedirectedAuthentication.
• Security.RestrictedAdminMode implies DisableCredentialsDelegation and RestrictedLogon.
• The low-level security flags are only written into the external session when External.UseMsRdpExHooks is enabled.
• AuthenticationServiceClass is not written to the generated .rdp file and should be treated as an embedded-mode setting.

Example:

control.RdpConfiguration.SessionMode = RdpSessionMode.External;
control.RdpConfiguration.External.UseMsRdpExHooks = true;
control.RdpConfiguration.External.MsRdpExSearchPaths.Add(
    Path.Combine(AppContext.BaseDirectory, "MsRdpEx"));
control.RdpConfiguration.External.SelectedMonitors = "0,2";
control.RdpConfiguration.External.AdditionalRdpSettings.Add(
    new RdpFileSetting("disableconnectionsharing", RdpFileSettingType.Integer, "1"));