Describe the bug
After adding a Cover Image block it displays a tiny toolbar on top of the image, however there's no indicator or even a flashing cursor, to show where you're actually supposed to click to insert text, or even that you can actually insert text.

This is just one of the many blocks that are incredibly frustrating to use because of the poor UI and lack of visual indicators!

To Reproduce
Steps to reproduce the behaviour:

1. Add a cover image
2. Try and work out where you have to click to add text

Expected behaviour
I shouldn't have top spend 5 minutes clicking around on the image to try and find the insertion point so that I can add some text

Screenshots

macOS Sierra 10.12.1 (16B2659)
Firefox Quantum 60.0 (64-bit)
WordPress 4.9.6
Gutenberg 2.8.0