I realize this isn't exactly what you wanted, but I think it's pretty close. Here's what I did.
1. Rename "Sum of Sales" to "Exclude," Duplicate that sheet, then rename this new one to "Compare."
2. Drag "Compare" into the Dashboard below "Excluded," Click Dashboard>Actions from the menu bar, edit Filter 1 to only target "Department2" and "Excluded," Click OK.
3. Click Add Action>Filter and make the source "Department2" and the target "Compare." Run the action on Select and then click OK.
4. Go to "Department2," right click the Action Filter and select Edit Filter. Click Select from list and then click the Exclude button and click OK.
5. On the "Excluded" and "Compare" sheets, drag SUM(Sales) to Columns and right click the axis. Set the Range to Fixed, click OK, then right click the axis again and deselect Show header.
Now, the dashboard should behave the way you intended.
Example1.twbx 2.1 MB
Okay this works for one dashboard.
I thought I could adjust it to more Dashboards but I cant
Is there a possibilty to use the selected filters as temporary variables?
My idea is to create a new "calculated field", for each selected filter, like:
"Filter 1 Sales"
SUM(Sales) FOR Department = [Filter 1]
This would be ideal. Because I would need to define more than one of these
EDIT: Basically I then want to use one column two times, divided by the two filters. LIke this