Image caption styling can not be changed

[peter-eL]

If we have some text styling applied and insert an image with a caption into the area - the styling can not be changed from the image caption anymore.

Repro steps:

1. add 2 lines of text to editor, apply some style (for example strikethrough)
2. insert image between the two lines, add a caption
3. the caption has the styling as the other text, and it can't be removed. Instead it creates a new line when trying to remove the styling.

Browsers: any Version: 3.2.3, but also reproducible on your demo website