Add opacity (transparency) to hover box / Allow it to be outside the plot

Plotly hover box has no transparency to it, which causes it to cover other data points, compromising the visual analysis of the data. Example:

Ideally it would allow box transparency like these one from dygraphs, which displays the hover text but does not cover/hide the region beneath it (http://dygraphs.com/tests/legend-values.html)

Additionaly, it could be great to have the possibility to show the tooltip/hover box information outside the plot, again to not cover any part of the plot and enable clear visual inspection. Another example from dygraphs:

Highcharts and dygraphs have those options as default.

There is some related discussion/request here: https://community.plotly.com/t/custom-hovertext-obstructs-plot-view-opacity-bottom-of-plot/9065

Changes like these would allow Plotly to be an excellent tool for financial plots and to be adopted by many more analysts from finance field.

Plotly is the best graphing tool in my opinion and I would like to stick to it, so I really appreciate if you can consider this request. Thank you for the awesome work.

Non vengono indicati file, test o punti di ingresso. Inizia individuando l'implementazione di hover-box del repository e consultando la discussione della community collegata; quindi confronta il comportamento di trasparenza richiesto e il comportamento fuori dal grafico con gli esempi di dygraphs. Il lavoro è completato quando entrambe le opzioni di visualizzazione dell'hover funzionano senza oscurare i dati tracciati.