change text background twice, cause the color to be lost

[Anas]

Steps to reproduce

1. Write a text in the editor (2 line of text).
2. Select it and change the text background color.
3. Click in the middle of the first line of text.
4. Change the background color again.
5. Note that same thing happens when change the text color.

Expected result

The background color for the whole first line doesn't change until the user select the first line then change the color, or at least change the background color to the new selected color.

Actual result

The background color for the whole first line will be lost.

Other details (browser, OS, CKEditor version, installed plugins)

Chrome Version 48.0.2564.97 m Win 8.1 CKEditor version 4.5.5 (also active on the live website and the nightly build). You can use the default config on the website demo, also i Attached is my build-config.js.