App icon reappears when opening URLs from certain applications

[zzamboni]

Hammerspoon version 0.9.76 (5104)
macOS 10.15.1 (Catalina)

When Hammerspoon is set to be the default URL handler and the app icon is set to hidden, sometimes the app icon reappears when Hammerspoon is invoked as the URL handler. When this happens, opening the Hammerspoon preferences and enabling/disabling the corresponding option makes the app icon disappear again.

The following minimal init.lua serves to reproduce the problem:

function dispatchURL(scheme, host, params, fullUrl)
   hs.printf("Dispatching URL '%s'", fullUrl)
   hs.urlevent.openURLWithBundle(fullUrl, "com.google.Chrome")
end

hs.urlevent.httpCallback = dispatchURL
hs.urlevent.setDefaultHandler('http')

The puzzling part is that this seems to happen depending on the application from which the URL is invoked. Here's an informal and incomplete list of my experiments with some of the apps I use:

• Happens when clicking on a URL in

  • Microsoft Outlook
  • Preview.app
  • Messages.app

• Doesn't happen when clicking or opening a URL in

  • open terminal command
  • Microsoft Teams
  • Terminal.app (i.e. cmd-double-click on a URL in the Terminal)
  • Station (https://getstation.com/)
  • Evernote

[zzamboni]

For now I'm using the following as a workaround :)

hide_icon_timer = hs.timer.doEvery(30, hs.dockicon.hide)

Update: don't use this, as it steals focus from the current window every time the timer runs. I tried wrapping hs.dockicon.hide in a function that gets the current window and then focuses it afterwards, but the result seems to be the same.

[zzamboni]

I just noticed there's been a lot of discussion around this topic in #2261, so I'm closing this issue in favor of that one.