The review request

https://git.reviewboard.kde.org/r/114712/

adds support for BalloonStyle colors for the background and text.

However looking at

https://developers.google.com/kml/documentation/kmlreference?hl=de#balloonstyle

there are still some attributes not covered yet:

• the text attribute is not covered. It should be added including the $[name], $[description], $[address], $[id], $[Snippet]  variables
• the displayMode attribute is not covered yet.

Use the example in the KML reference to verify that your implementation works.