[5.4.0] Option to flash tray icon with new message

[Jon8RFC]

Is your feature request related to a problem? Please describe.
The small static dot is helpful, but can be difficult to spot, especially for older people who need loud sirens and waving flags to get their attention.

Describe the solution you'd like
Something a little more visible but not overly obtrusive would be excellent, like "flashing" the tray icon on and off.
Maybe just an empty image as the "off", or if some OSes don't like that, then a very transparent image.

Additional context
I know this is for VB, but maybe it's helpful for the code research phase