Hi Derek,
thanks for your donation! I'm glad to tell you that we've now added an "(Un)Comment" feature to the text editor of BaseX, and closed the corresponding GitHub issue [1]. Feel free to check out the latest snapshot [2]. As we have a rather minimalistic interface, we haven't added an extra button. Instead, you may use the shortcut "Ctrl + /" to comment and uncomment highlighted texts or lines in XQuery or XML files.
One day in future we'll document all the available GUI shortcuts (or hope that someone's interested in extending our Wiki [3]). For now, you can have a look into our shortcut mappings in the source code:
https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/gui/lay...
All the best, Christian
[1] https://github.com/BaseXdb/basex/issues/144 [2] http://files.basex.org/releases/latest/basex-6.7.2-SNAPSHOT.jar [3] http://docs.basex.org/wiki/Main_Page