alt+click doesn't mark a message as unread on slack webapp

Question

From slack's Keyboard shortcut menu (ctrl+/):

Mark a message as unread --- Alt and click message

But this doesn't work :(

When I alt+click I get a clutched hand icon.

Running ubuntu 16.04.

Answer 1

alt+super+click works.

The problem is that alt+click is grabbed by the OS.

See more info here: https://askubuntu.com/q/521423/13330