[Kst] Vector skip patch ?

[Brisset, Nicolas]

> AFAIKT, This would work in static mode, but in real time 
> count-from-end mode, it will not behave well:  If you are 
> counting from the end, with skip on, I assert that these 
> three things should be true:
> 	-My plots should only update every SKIP frames (not 
> every frame, as would happen with the patch) and 
Hum, that is not quite what I expected. I thought the last point
available would always be shown as in many cases it is very important.
But then, that is bad for performance as it would require updates every
time new data arrives regardless of the skip value. I guess we should
favor performance here, as a user who requests to skip points should be
aware of it and probably does so for performance reasons...

One thing I find potentially confusing for the user though is the
"Range" field in the UI: is it the (max) size of the resulting vector,
or the number of the last frame considered ? I have just made some
experiments (with the patch applied) and I'm completely confused right
now... What I'd personally find the most useful is to specify the number
of points in the resulting vector, but I'm not sure if fits well with
all cases... It is really not so easy to have a clear overview of user
expectations and constraints to consider. I think we should write this
down somewhere and make sure it is clear before actually implementing
it. It will be useful for documentation anyway :-)