Tab key in modals tabs through elements outside the modal

[ghost]

Describe the bug
Inside a modal dialog, pressing the Tab key repeatedly moves focus to the next items inside the modal, then also to items outside it.

To Reproduce

1. Open a modal dialog, e.g Create Card.
2. Press Tab key a dozen times.
3. Observe that the focus eventually goes to menu items, chapters, scenes, etc.

Expected behavior
When the last element in the modal has focus, pressing Tab again should focus the modal's first element.

Screenshots
In the image below, after opening the modal I was able to focus the "New Scene" button. Pressing Enter key at that point opens the New Scene dialog (the two modals are open at the same time).