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Adding chords
When editing a show, you get a few buttons at the center bottom. One of them displays a "note" icon with the label "Chords". Click on it to enable chords mode. This will display any existing chords, and add a "+" button to the top right corner of all textboxes. Click that button to add a chord, or right-click to choose from a list.
All the chords can be dragged around in the text when chords mode is enabled. (This is currently very buggy)
Show chords in stage display
You have to enable the chords in the stage display by selecting either a slide textbox and enabling "Chords" on the right side.