lpe UI improvement

[jfb]

I think lpe have grown enough to deserve some UI emprovements.

It would be nice to easily add labels in the pannel that are not associated to a parameter, just for readability

It would be nice to be able to split parameters into basics and advanced; the latter would be gathered into some rollups to save space and readability.

It would be nice to have preset system: for complex effects (hatches for instance), the look and feel of the result depends on a lot of parameters. Tweaknig them until you get what you want might be a bit tedious, particularily for beginners. A collection of presets would be nice... you would pick a name in a drop down list, and this would set all the parameters for you to achieve that particular result. Even better if the user can register he's own presets.

Unfortunately, I have no idea how to implement this kind of thing. I believe this can be done by hand for each lpe if you know how to do it. Having a kind of standard API for that would be helpfull however.

Ah, and btw, one more technical point: being able to dynamically create or remove knotholders would be very usefull for complex effects...

Thanks!