We can't place conditional visibility on custom widget's but it would be very nice if the MX framework atleast triggered an event (the update event for example) when the widget becomes invisible/visible due to conditional visibility that gets triggered due to changes on the object that trigger the conditional visibility.
Right now the widget is not aware of this unless the conditional visibility change goes with a microflow that just fully updates the object and the widget is subscribed to updates from the object or attribute that changes the conditional visibility.
A nice bonus would be saving the state of the visibility on the widgets this scope or having a function to retrieve the state.
The reason this became more important is due to the fact that some weird magic happens in removing/readding nodes since the change in conditional visibility behaviour implemented in MX 6.10.x