Adds a grob as a new row at the bottom of an existing canvas.
Usage
canvas_add_row(canvas, grob, height)
Arguments
- canvas
A `gtable` produced by `new_canvas()`.
- grob
A grob/gtable to insert as the next row.
- height
A non-negative `grid::unit` giving the row height.
Value
The updated `gtable` with the new row added.