Fixes hiding of AppIndicator. (Closes #132)

[sphh]

Setting .visible to False calls https://github.com/moses-palmer/pystray/blob/6ad09b90ebbd25cfd7e7de1abf830a382577b052/lib/pystray/_appindicator.py#L60-L61 This disables all functionality of the AppIndicator, but does not hide it. Even if .visible is set to True again, the icon is not updated and stays in that disabled state.

How hiding of the AppIndicator can be done is shown in

• https://stackoverflow.com/questions/52724273/appindicator3-indicator-is-there-a-way-to-hide-show-it-at-runtime#answer-52727457
• https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators#Porting_Guide_for_Applications

[moses-palmer]

Thank you very much for your contribution!

[sphh]

You are more than welcome!

Thank you for writing pystray!