changing hidden events on multiple channels loses information
when changing events with multiple channels marked, all channels have the same events hidden afterwards regardless of what they had hidden before.
steps to reproduce:
1) mark two or more channels, at least two of which with different events hidden:
i.e. mark one channel with mode changes hidden and one with mode changes visible
2) with the channels marked toggle a second event type (i.e. day changes)
events other than the one toggled remain unchanged (i.e. still one channel with mode changes hidden and one visible)
all marked channels have the same events hidden after toggling any of the event types.