Often, a dynamic and a hairpin need to be set on the same note. I've found this to be useful:
!NoteWorthyComposerClip(2.0,Single)
|Clef|Type:Treble
|TimeSig|Signature:Common
|Dynamic|Style:mf|Pos:-7|Justify:Right|Placement:AtNextNote
|RestChord|Dur:8th|Opts:Stem=Up,VertOffset=2000|Dur2:Whole|Pos2:0
|Rest|Dur:8th|Opts:Stem=Up,Diminuendo,VertOffset=2000
|Rest|Dur:4th|Opts:Stem=Up,Diminuendo,VertOffset=2000|Visibility:Never
|Rest|Dur:Half|Opts:Stem=Up,Diminuendo,VertOffset=2000|Visibility:Never
|Note|Dur:Whole,Grace|Pos:0z|Opts:Stem=Down,XNoteSpace=1,Muted
|Bar
|Dynamic|Style:mf|Pos:-7|Justify:Right|Placement:AtNextNote
|RestChord|Dur:8th|Opts:Stem=Up,VertOffset=2000|Dur2:Whole|Pos2:0
|Rest|Dur:8th|Opts:Stem=Up,Diminuendo,VertOffset=2000
|Rest|Dur:4th|Opts:Stem=Up,Diminuendo,VertOffset=2000|Visibility:Never
|Rest|Dur:Half|Opts:Stem=Up,Diminuendo,VertOffset=2000|Visibility:Never
|Bar
|Rest|Dur:Whole|Opts:Stem=Down
!NoteWorthyComposerClip-End
The first measure uses a grace note to stop the hairpin at the barline, while in measure 2 the hairpin is allowed to continue. If you have layers or other staves, you may have to adjust the durations of the hidden rests for the effect you want.
This would be more flexible if hairpins were always visible, but alas they inherit visibilty from the first note/rest. From a playback standpoint, hairpins function the same as cresc., decresc. and dim., whose visibility can be controlled.
Edit: added strikethru due to <this reply> (thanks, Peter). Hairpins are visible if any note they encompass is visible. I still think they should always be visible, but NWC's handling is not unreasonable.