The cursor in the book signing GUI doesn't turn fully invisible when blinking

The Bug:

The cursor in the book signing GUI doesn't turn fully invisible when blinking.

Steps to Reproduce:

1. Place down a sign, look at the cursor, and take note of how it blinks by turning visible and invisible.
2. Obtain a book and quill, open it up, look at the cursor, and take note of how it blinks by turning visible and invisible.
3. Click on the "Sign" button in the book and quill GUI and look at the cursor.
4. Take note as to whether or not the cursor in the book signing GUI turns fully invisible when blinking.

Observed Behavior:

The cursor doesn't turn fully invisible when blinking.

Expected Behavior:

The cursor would blink by turning fully visible and invisible, following the behavior of other similar GUIs.