Hi
I will like to suggest an option for chat window.
Currently, Spark Client doesn’t have an option to separate the chat window.
Only tabbed chat window is the default option in Spark.
I hope this will add in the next Spark Client release.
Thank you so much! 
Hmm… I think I posted this suggestion in a wrong section. Sorry, guys.
You can move your topic by clicking on the pencil near the topic name and then selecting new category. Select Spark Support.
There is a long standing ticket for your request https://issues.igniterealtime.org/browse/SPARK-893
One contributor even started working on it 10 years ago, but never finished. As Spark currently has no active developers i doubt this will ever be implemented. I can’t even say if new version of Spark will ever be released again.