Playing poker across multiple sites poses a problem when each individual site fights to steal the focus from your other tables. For example, you could be trying to act on a Pokerstars table in your stack, and a FullTilt table needs action and could pop in front of the Pokerstars table, causing you to misclick and take action on the FullTilt table instead.
StackAndTile solves this problem. It will keep track of the tables in the stack needing action, and will only pop them up after you have acted on the first table.
For this to work, you will have to turn OFF each pokersite's option to pop their tables to the top. If a site doesn't have the option to turn this off , then it will continue to fight with StackAndTile and you may have problems. SaT has its own option to handle this. It is the first checkbox in Advanced Options for "Activate (focus) table when action required". By default, this is turned ON, so you don't need to do anything within SaT. You just need to turn off the settings within your poker sites.
Here are some examples of the options in the clients to turn off:
The best thing to do is look at each site's documentation in the supported sites list.
If you ever decide to stop using SaT, then you will probably want to turn these settings back ON within each poker client.