What you suggest will fast become confusing and difficult to follow. It's better to keep layouts in an immediately recognizable form. Also, I've built in a fl

What you suggest will fast become confusing and difficult to follow. It's better to keep layouts in an immediately recognizable form. Also, I've built in a flexible window scaling feature to assist with fine tuning layouts. For example if you create "123", and want to change the "3" into a 2x2 grid, instead of copying lines or retyping the layout, you could just "--scale 1 2x 2x --scale-replace" (assuming window 1), then edit the session file and fill in the details. It also has the ability to down scale. Play around with it and you'll see how helpful it is. Once you get the hang of designing layouts, you may find most general use layouts can be typed up pretty fast. As mentioned in another comment, there will be support for YAML in version 1.1. I don't know how soon that will be, since I am working on another project right now, but keep an eye on tmuxomatic, it should be soon. Thanks for the feedback!