If I understand correctly, you only want to see sheet 2 contents when hovering over sheet 1.
Put sheet 2 on the dashboard and create a filter action like this:
The trick here is exclude which will hide the sheet when you are not hovering on sheet. To really hide the sheet, you will need to turn off the title and the borders.
If you want to value to stay until you hover on something else, select leave filter. If you want to see the total value when nothing is being hovered, select show all values.
Thanks for the response. Unfortunately in my original tableau file I can't have the sheet on the dashboard because of real estate issues. That's why I was wondering if it was possible to have a dashboard action like the one I stated in my post.
Both sheets will need to be on the dashboard to use an action. You could try and hide it so it expands upon the hovering or pops on or off the screen.
How can I hide a sheet on a dashboard ??