original idea: https://community.tableau.com/ideas/3636
Filter actions area great, passing parameters from one viz to another is very helpful, however did you ever notice the one thing you can't pass is a parameter control? A very common report is one with information by date, and then the ability to then jump to a detailed viz passing perhaps the department and date that shows the month you selected as well as the previous month (or even a year...to show month over month or year over year). However Tableau doesn't allow you to pass a date as a parameter.
See the attached example using Superstore data where we have a Sales by Department/Month. When I select a point on the graph for say "Technology" Department for the month of Nov 2011, I would like to see the tables below filter to the Department = Technology and to the date = Nov 2011....and since those tables are "current month and previous month", I would expect it to pass the current month selected (which is Nov 2011) and therefore show Oct AND Nov of 2011. The only way to do this currently is to create a parameter for date and force the user select a date from the parameter in addition to selecting the point on the graph.