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

What is the current behavior?
when i typed multi line text -> move cursor to start of second line -> hit the spacebar -> removed whole previous text lines

it's happend on facebook.com, draftjs.org and my own project

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. You can use this jsfiddle to get started: https://jsfiddle.net/stopachka/m6z0xn4r/.

What is the expected behavior?
just regular space append. same like office program.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?

i tested, and some browser, OS happens different bug.
MacBook pro(version 10.12.4)

• chrome 57.0.2987.133 (64-bit) ==> remove previous text line
• safari ==> 'space' is input but didn't render anything

Windows 11

• IE11 ==> work fine
• Chrome 56.0.2924.87 ==> 'space' is input but didn't render anything
• FF 51.0.1 (32bit) ==> 'space' is input but didn't render anything