Fix tooltip context and position on click

[dmitrizzle]

Is your feature request related to a problem? Please describe.
Nope.

Describe the solution you'd like
I would like to have the tooltip stay in position and the data shown in the tooltip to remain constant when user clicks on a point. Clicking outside tooltip would resume normal interaction (tooltip appears on hover and moves with crosshair). I think this can be accomplished by forcing the touch interaction functionality on screens with mice.

Describe alternatives you've considered
There's no API for this as far as I can tell, so I figure this would require a mode within the package. If not, please let me know!

Additional context
Tooltips on my graph will include links which will need to stay on screen for users to be able to click them.

[plouc]

This is more a popover behavior I feel, and something which could be implemented using the event handlers + potentially a custom layer.

With the current implementation of the tooltip, this would require a lot of changes on all chart types, introducing an optional fixed position, and having conditional handlers.

While I think the feature could be useful, and has been requested a few times in the past already, that's not something I'll be able to implement in a near future.