`MixedRealityKeyboard` calls `onSubmit` when X is pressed for `TMP_InputField`

[talothman]

Describe the bug

When using the MixedRealityKeyboard component to trigger the native keyboard on HL2, clicking the X will call onSubmit for the TMP_InputField that is being edited.

To reproduce

1. Open any sample MRTK ready project and scene.
2. Add a TMP_InputField and add the MixedRealityKeyboard component on any existing GO in the scene.
3. Add a script that binds to the TMP_InputField.onSubmit event.
4. Deploy to device.
5. Click on the input field and the keyboard will come up.
6. Click the X button on the keyboard.

Expected behavior

onSubmit should not be called.

Your setup (please complete the following information)

• Unity Version [e.g. 2020.3.29f1]
• MRTK Version [e.g. v2.7.3]

Target platform (please complete the following information)

• HoloLens 2

[IssueSyncBot]

We appreciate your feedback and thank you for reporting this issue.

Microsoft Mixed Reality Toolkit version 2 (MRTK2) is currently in limited support. This means that Microsoft is only fixing high priority security issues. Unfortunately, this issue does not meet the necessary priority and will be closed. If you strongly feel that this issue deserves more attention, please open a new issue and explain why it is important.

Microsoft recommends that all new HoloLens 2 Unity applications use MRTK3 instead of MRTK2.

Please note that MRTK3 was released in August 2023. It features an all-new architecture for developing rich mixed reality experiences and has a minimum requirement of Unity 2021.3 LTS. For more information about MRTK3, please visit https://www.mixedrealitytoolkit.org.

Thank you for your continued support of the Mixed Reality Toolkit!