Grabbing keyboard input on MacOS

[proteins247]

I've searched around grabbing keyboard input (#26) and I read it can be toggled by Ctrl+Alt+Shift+G or by adding "/grabkeyboard always" to the launch options in the .exe file.

But I'm using MacOS, and I can't enable grabbing keyboard input. Is this feature unsupported for MacOS?

[dcommander]

Keyboard grabbing isn't implemented in the Mac TurboVNC Viewer (note that it doesn't appear in any of the menus or the command-line usage) because there isn't a strong need for it on Mac clients. Although I try to ensure that the TurboVNC Viewer works with Windows and Mac VNC servers, its primary use is as a client application for the TurboVNC Server, and the TurboVNC Server only works on Linux, FreeBSD, and Solaris/x86. As such, the primary purpose of the keyboard grabbing feature is to send special window manager keystrokes (Alt-Tab, Alt-Esc, etc.) to the server. Since macOS doesn't intercept those keystrokes, sending them to the TurboVNC Server already works with Mac clients without the need for keyboard grabbing.

If there is a particular use case that you feel would justify keyboard grabbing on Mac clients, then please let me know. AFAICT, the only real purpose for such a feature would be to send Mac-specific window manager keystrokes (Command-Tab, etc.) to a Mac VNC server, and whereas I'll implement anything for money, that particular configuration (Mac-to-Mac) isn't a strategic priority for TurboVNC.

[proteins247]

Here's an example where keyboard grabbing would be useful:

1. Ctrl+1/2/3 in the file browser to change the view mode (MacOS grabs it for workspace switching)

Additionally, I am interested in sending Cmd to the session (and then within linux remap it to alt (e.g. https://unix.stackexchange.com/questions/86933/swap-alt-and-super)) so that I can hit usual Alt+Key combinations.

I understand if these are not priorities. thanks

[dcommander]

The feature is technically feasible. It would just require funding for my labor.

[proteins247]

I see.

Reporting on a failed workaround: I use Emacs, and common shortcuts include Alt-F (forward one word) and Alt-W (copy). I realized that it's possible, once connected to a Linux desktop, to use xmodmap to rebind Command (seen as Super) to Alt. But pressing Cmd-F and Cmd-W activates TurboVNC shortcuts full-screen and close connection respectively. In MacOS Preferences, it's possible to rebind application shortcuts. I tried this with "Full Screen" and "Close Connection," binding them to Ctrl+option+cmd+KEY (so that activating these shortcuts is difficult), but it appears that TurboVNC doesn't respond to these rebindings. The application menu shows the new combinations next to the menu items, but the combinations don't work. Instead, the old shortcuts remain active.

[dcommander]

I'm not surprised that that doesn't work, since the accelerator keys for the Mac menu are hard-coded. I could use the remapped shortcut keys if there were a way to get that information through Java, but I don't know if such is possible.

I certainly understand the desire to send Ctrl+1/2/3 to the server, although I consider that to be a softer requirement than sending Alt-Tab, since Ctrl+1/2/3 is window-manager-specific. As far as remapping the Command/Super key to the Alt key, that's a personal preference hack, so I don't feel particularly guilty that it doesn't work. Linux software is not generally designed to use the Super key for that purpose.