Also, alt + left click doesn't bring up the halo, but alt + shift + left click.
If that's true, it's a bug.
It's probably the window manager. By convention, many X11 window managers use Alt-click for window manipulation (Alt+left click is often "raise window" or "move window").
Applications shouldn't be written to assume that they can use Alt+mouse. Try using one of the other keys, maybe the "Windows" key or the "menu" key as a modifier.
Tom
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