Manipulate Chart Display from Matrix

[RPYee]

I have a matrix that interacts with a line chart next to it.  When one of the columns is selected in the matrix, the line chart reacts appropriately:

However, if no columns are selected in the matrix, ALL lines are displayed in the chart:

When there is no column selected, I'd like to see the line chart represent the results of the "Total" column:

I am extremely new to PowerBI. In fact, this is my first project.  I am open to any and all suggestions on the best way to accomplish this objective.  

Thanks, in advance, for any help you can provide!

[lbendlin · Accepted solution]

Read about FILTERS() and HASONEVALUE().  Then read about using measures as visual filters.

[RPYee]

While I'd have liked something a bit more specific, it did point me in the right direction.  I'd have been searching forever without this help.  Thanks!!