Is there a way to hide the App in Dock after adding it to menu bar?

[dkguo]

I added <key>LSUIElement</key> <true/> to Slack’s Info.plist and resigned the app, so it can be hidden from Dock. However, with this method, I can’t launch Slack screen by clicking icon in the menu bar. Is this because Slack is now a agent application, which is different from opening the window of normal application?