The footer (as shown in this image https://github.com/kanbantool/scripts/blob/sdk-scripts/save-done/preview.png; with 'save' and 'save and close' button) was removed some time ago. For less experienced users, this means that there is confusion between the "X" (when creating tasks, which is 'cancel') and the "X" (when editing cards, which is close [after auto-save]).
This script adds a 'close' button to the bottom (footer) of the card, which closes the card. Clicking the "X" in the top right is thus no longer necessary.