If you want vibrato you need to continuously add to the input frequency of the note to play
And as midi is control domain not audio you need to take a snapshot of the LFO to convert to control domain
vib.pd

[list length]
is what you need

Or you could hide a bang at each end of the slider to nudge the value and use the centre area of the slider to scroll ( there will be a dead zone for scrolling at each end where the bang takes the focus)
nudge-slider.pd

Edit:
Weirdly nudging to a lower value, steps 2, but changing the message [-1( to -0.5 fixes that

If you hold the shift when sliding you get a finer adjustment

rename the array to $0-wavemon and the tabwrite to [tabwrite~ $0-wavemon]
.
The $0 (dollar zero) represents a unique number each time the abstraction is instantiated

500 refers to index 500 not 500ms. in the example the array size is 1000, so start half way, generally audio makes very large arrays, therefore a very large number is required

on windows and linux right mouse click brings up a menu for help, I'm not quite sure about macs (option click?)

This may work for missing filenames in an abstraction, if there is no symbol a bang is passed to the rejection outlet otherwise the symbol passes through

@RayManiac a bit remiss of me not to mention a minus frequency value will play in reverse.
better late than never

So, Purr Data has a dropdown list object. and very nice too!

Here is a vanilla effort using hsliders
its colourable - good
its width can be set - good
the list will eventually cause a scrollbar if it runs off the bottom of the patch but require another event to cause it - bad good
its list is not scrollable - bad
it can only list symbols - bad
it needs all 5 arguments to instantiate - bad
and worst of all it need a local copy of the abstraction to be edited with the name of the main patch - -bad bad

I wasn't going to upload this but its quiet here, so here it is, it might be useful
Cheers
Balwyn

droplist.zip