Panels are different sizes when converting ggplot plot with facets

When converting a ggplot plot with facets to a plotly object the panels are different sizes. Margins are not subtracted from top and bottom rows so these panels end up being taller. This makes it hard to compare among panels. Margins for top and bottom of panels are equal so longer x-axis labels result in large margins on tops of panels with large spacing between panels and a low data-ink ratio.

library(dplyr)
library(ggplot2)
library(plotly)
library(reshape2)

p <- ggplot(data = tips,
            aes(x = sex, y = total_bill)) +
  geom_jitter(width = 0.1, height = 0) +
  facet_wrap(day ~ time, scales = "free_x", ncol = 2) +
  theme(axis.text.x = element_text(angle = 45),
        strip.text.x = element_text(size = 8, 
                                    margin = margin(t = 1, r = 0, b = 1, l = 0, unit = "pt")))

q <- ggplotly(p) %>% 
  plotly::layout(margin = list(l = 80, r = 0, t = 100, b = 100, pad = 0))

d <- rbind(q$x$layout$yaxis4$domain, q$x$layout$yaxis3$domain, q$x$layout$yaxis2$domain, q$x$layout$yaxis$domain)
df <- data_frame(lb = d[,1], ub = d[,2]) %>% 
  mutate(range = ub - lb,
         panelSpacing = lb - lag(ub))

使用提供的 ggplotly() 示例重现该问题，并检查在 d 中收集的 y 轴域值。首先跟踪 facet 面板和布局边距是如何转换的，然后验证顶部和底部面板的大小相等，并确认间距反映了配置的边距。