Links to callbacks
A has a tooltip
graph LR;
A-->B;
B-->C;
click A callback "Tooltip"
click B "http://www.github.com" "This is a link"
click C callback "Tooltip C1"
Links to urls
graph LR;
A-->B
B-->C
click A callback2 "Tooltip3"
graph LR;
subgraph S1
a-->b
end
subgraph S2
c-->d
c-->d
end