Add hints/tooltips indicating required actions to trigger specific buttons in Canvas

Goal:
Show error message to the end-user without any action.

Example: users can currently click on a button and execute an ETL job without selecting the correct (base) elements in the comboboxes (e.g., choosing "All cost centers" is not allowed).

Behavior:

• How I currently implement this: if invalid elements are selected, Button A is shown. Clicking it displays no message box. Only when hovering above it a message appears:
  "Please select base elements only." Button B with the ETL job is hidden.

• If valid selections are made, Button A is hidden and Button B appears, which runs the ETL job.

Requirement:
We need an action type that allows displaying a custom message box with free text only, without triggering any other action.