[vtk-developers] New feature: improved hover support

[Jeff Baumes]

> This is probably a dumb question: Would it be possible to register an object
> with the renderer when extra renderers are needed for picking etc. and then
> only do the extra work when something is registered?

Yes, something like this would be a better approach. Instead of having
an option DisplayHoverText on the view, the view would just enable
hovers if any representation says that the user wants to see hover
data on it. Representations are already registered with the view, but
could contain a new IsHoverable method that could be queried by the
view when it is deciding whether to do a pick render for hovers. In a
graph representation, for example, IsHoverable would return true if
either vertex or edge hovers were turned on.

Is this near what you intended?

Jeff