If you have normalizations enabled, you don't need to "switch into a vertical stack"

Given this layout:

    h_tiles
    ├── window1 (focused)
    ├── window2
    └── window3

`move left` will produce this layout:

    h_tiles
    ├── window1 (focused)
    └── v_tiles
        ├── window2
        └── window3