RDCMan v3.21: Local keyboard layout not synced to remote session (mstsc works correctly)

[TRiebesel]

Summary

When connecting via RDCMan, the client's local keyboard layout is not applied to the remote session. Instead, the remote session uses its own default keyboard layout. Connecting to the exact same target with mstsc.exe works correctly and syncs the local layout as expected.

Environment

• RDCMan version: 3.21.0
• Client OS: Windows 11 25H2
• Client keyboard layout: German (DE)
• Target OS: Windows 11 25H2

Steps to reproduce

1. Set the local/client machine's active input language to German.
2. Open the connection to a target server in RDCMan and connect.
3. Observe the keyboard layout inside the remote session.
4. For comparison, connect to the same target using mstsc.exe with the same client machine.

Expected behavior

The remote session should use the client's active keyboard layout (German), matching the behavior of mstsc.exe.

Actual behavior

The remote session uses its own/default keyboard layout instead of the client's German layout. This only happens with RDCMan; mstsc.exe against the same target behaves correctly.

Additional notes

• Verified this is not caused by the IgnoreRemoteKeyboardLayout registry setting on the target (server-side layout sync is not disabled, since it works fine via mstsc).
• This started happening after upgrading RDCMan (currently on 3.21, no changelog available for 3.20/3.21).
• Happy to test against an older RDCMan build if useful for narrowing this down to a specific version.

[VTorstai]

Same thing with version v3.20.
Target OS doesn't matter, the same thing happens even when connecting to Linux xrdp-desktops. And connecting to Windows Servers 2016 / 2019 / 2022 /2025.