When you click on the graphics area, you will see this popup toolbar:
How can you customize it to add more icons to it?
Solution
You need to go to Menu --> Tools --> Customize --> Shortcuts -> Select View which activates View toolbar ->
Now go to Commands to find the one you would like to add and drag it to this View toolbar. As you can see Trim Curve command (circled in red) was added.
Notes and References
Hardware/Software Configuration
Platform: na
OS: windows
OS Version: n/a
Product: NX
Application: SYSENG
Version: V1899
Function: UI_TOOLS
Ref: 001-9697867