Does anyone have made a 'htmlmixed' + 'Velocity' mode for codemirror? Or anyone can advice how to achieve that?
You might be able to get somewhere using the mode-multiplexer, if there are specific strings that you want to use to switch mode on. But it looks like Velocity would require something more advanced. So you'd have to write your own super-mode, similar to what the htmlmixed mode does, which intelligently switches between modes.