Feature: Use Android Accessibility Service​ to capture global key events (Win Key, Alt+Tab)

[DanielToyama]

Problem:
When using a physical keyboard with AVNC, certain key combinations (like Win, Alt+Tab, Win+Tab) are always captured by the host Android/OS instead of being sent to the remote VNC session. This breaks the workflow when trying to use the corresponding functions (e.g., Start Menu, application switching) within the remote desktop.

Feature Request:
Implement a "Keyboard Shortcut Interception" mode or option. When enabled, AVNC should capture designated system-level shortcuts and send them directly to the remote VNC server, preventing the host OS from handling them.

Specifically, it would be ideal to intercept:
• Win / Super key: To open the remote Start Menu.

• Alt + Tab: To switch applications within the remote OS.

• Win + Tab / Alt + Esc etc.: Other common desktop navigation shortcuts.

Proposed Implementation:
This could be implemented as:

1. A simple toggle in the settings (e.g., "Capture system keys").
2. Or, more flexibly, a customizable key blocking list.

Benefit:
This provides a seamless keyboard experience, especially for users who primarily interact with the remote machine, eliminating the need to constantly switch focus between the host device and the remote desktop.

Thank you for considering this enhancement.

[gujjwal00]

AVNC already forwards these key events to server. Problem is that most ROMs don't dispatch these events to apps. And if OS is not providing the correct events to AVNC, there is nothing we can do about that.

[DanielToyama]

Thanks for the explanation. That makes sense.
As a potential solution, would it be technically feasible to use the Android Accessibility Service​ to capture these global key events at a higher permission level, bypassing the ROM restrictions? Some apps use this method to intercept system keys.

[gujjwal00]

Well, I haven't used Accessibility Service so I can't be 100% sure. But if it works and can be controlled with an opt-in setting, I don't have a problem with the feature itself.

However, I won't have time to test/implement this for quite a while. So if anybody wants to work on this, I would be happy to merge a PR.