Show position of text cursor in playback bar

[hikari-no-yume]

Seeking is already very pleasant in Hibikase, but you still have to scrub back and forth a bit to find a specific syllable or line. We could add a highlight to the playback bar that represents the position of the text cursor, based on surrounding syllable timing. Maybe we could only show it if it's far away from the playback position or something, otherwise it could be a bit distracting.

Perhaps even better would be if you could hold some modifier while clicking in the text to make the playback head jump.