Tix Vs Pmw which is better to use?

[Eric Texier]

My application needs a very dynamic widget package, It needs to add and
remove  widget constently.
I am looking also for something that will let me create more organic
widget like tree but on a free canvas.

- Do I have to be aware of some major difference before I should choose
one or the other?
- Is there an other package to be considered ?

Thanks
Eric Texier