WIP: event-widget: show a popover after right-clicking event
Currently event right-click opens event for editing.
The accepted semantics of right-clicking are that it presents options, not performs an action (open for editing) itself.
To fix this situation, show a popover with "Delete" (and maybe "Edit"?) option.
Closes #274 (closed)
Edited by Georges Basile Stavracas Neto