Backward selection from the start of a block is broken

[zbeyens]

Do you want to request a feature or report a bug?

Bug

What's the current behavior?

https://www.slatejs.org/examples/plain-text

Backward selection from the start of a block is not working correctly.

It looks that the cursor is moving when selecting

Chrome 78.0.3904.108
Windows 10
Slate v0.50.0

What's the expected behavior?

The cursor should not change its position when selecting with the mouse

[ianstormtaylor]

Is it just when using the mouse?

[zbeyens]

Using only Shift+Left, the backward selection breaks when traversing an empty block:

Using Ctrl+Shift+Left: breaks only when starting from an empty block:

[ianstormtaylor]

I think the original thing is a mouse-only behavior that is related to the zero-width spaces. I'm going to close in favor of #1971.