Plot shrank or expanded when activating or deactivating legend keys

Basically, when I double-clicked on the legend keys to activate or deactive them, the plot shrank or expanded. I posted the issue on StackOverflow and the user mnist found that it was the empty string that caused the problem.

Here is the reprex

p <- ggplot(mpg, aes(x = displ, y = hwy, color = factor(cyl), shape = class)) +
geom_point(size = 3) +
    scale_color_manual(values = c("4" = "#abd9e9",
                                  "5" = "#2c7bb6",
                                  "6" = "#ff7f00",
                                  "8" = "#d7191c")) +
    scale_shape_manual(values = c(2, 5, 16, 17, 18, 19, 25)) +
    guides(color = guide_legend(title = "Cyl", order = 1),
           shape = guide_legend(title = "", order = 2)) +
    theme_classic(base_size = 16)
p

ggplotly(p) %>%
    layout(xaxis = list(autorange = "reversed",
                        tickvals = c(2, 3, 5, 6),                        
                        ticktext = c("2", "", "5", "6"))) 

まず、提供された R reprex を ggplotly で実行し、凡例キーをダブルクリックしたときのプロットのリサイズを再現します。凡例のアクティベーション時に空の凡例タイトルまたはラベルがどのように処理されるかを追跡し、その後、キーの切り替えによってプロットの寸法が変わらなくなったことを確認します。