When you have a condition on a field or add an action button to your Salesforce table, and you set a custom action as a result, the modal window for configuring the custom action looks almost like the original (which is the Modal that opens from the Salesforce action button).
The reason I say “almost” is because a few things were missing - and we decided to add them to the window:
1- Go to page
2- Redirect after finish
Enjoy!