I have a suggestion function: Find related events via global or instance variables.
When we created thousand of events, we may forget where we use the variables before especially changing something during design progress. The function work as below:
Mouse over a global or instance variable and right click.
Select "Find related events with this variable".
It will highlight all the events that using this variable.
I found out this is very useful especially for checking and clean-up progress. Hope C2 will have this function in the future release.