I’m trying to make an interactive plot that has a regression line on top of it. Here is the plot in the Vega editor and here is a gist of the Altair source (MRE). This is heavily influenced by this very nice SO example (thanks Andrii Syd).

Is there any way to do a log-log regression (both x and y axes are on a logarithmic scale)? Linear-linear, linear-log, log-linear all seem straightforward.

Altair now warns that selection_multi is deprecated and tells to use selection_point instead. I tried to replace it with same functionality with no success. How should I do it?