removed beep again, as it still kept beeping on me when switching tags in my window manager and sometimes even when just changing tabs. I also wonder if it's really worth, as i often copy some part of the webpage with the X11 selection while the command line is open and paste it there then. On the other hand, for novice users a beep might make sense if they wonder where their cursor is. For now at least i revert it, with a better fix, we can talk about it.

content/ui.js

@@ -714,10 +714,6 @@ function CommandLine() //{{{
                         !(modes.extended & modes.OUTPUT_MULTILINE) &&
                         event.originalTarget == commandWidget.inputField)
                     {
-                        let focus = document.commandDispatcher.focusedElement;
-                        if (focus && focus.ownerDocument == content.document
-                            || focus instanceof HTMLInputElement)
-                            liberator.beep();
                         commandWidget.inputField.focus();
                     }
                 }, 0);