Use Marginal Plots for TF-Visualization

[pantaray]

Not really a problem per se, more like a missing feature? Please elaborate In TF visualizations, it would be nice to have the option to show the time- and frequency-course of a user-provided toi/foi combination (in addition to potentially provided toilim/foilim specs) via marginal plots, akin to:

For "regular" (i.e., non-time-frequency representations) we could render a "cross-hair" to point at the selected toi/foi pair.