confusing sword icon to leave editing mode

[quenenni]

Is your feature request related to a problem? Please describe.
The icon to close the window when editing an image (a sword) is very confusing.

We had a group test with end-users to test all sort of things.
No-one was able to find how to leave the editing mode becasue the sword icon is never used for this.

Describe the solution you'd like
Change the sword icon with a X kind of icon

Thank you.

[joshtrichards]

Fixed in #2813