Open the Find pane (Ctrl+F/Cmd+F). Click on the syntax selector in the bottom right corner of the screen and select any syntax from the list. Bam, the Find input field is now treated as a full-blown buffer with its own line numbering and syntax!
This might be useful as a feature, but the way it works now it sure looks like a bug: the syntax indicator still shows the syntax of the file, the Find input field looks ugly, and there is no way to return it to normal.
Customer support service by UserEcho