How to disable scaling when mouse over some node which has scroll bar?

[yarcowang]

For example, I have a node which contains a div with scoll bar. When I try to scoll, the whole diagram is also scaling.
I want to disable scaling when mouse over some node (notice: the node might have not being selected yet) which has scrollbar.

Don't know how to implement it.

(I see in some case, you can define custom actions, and in another case, you need to implement states, I'm confused.)