Setting up parameters in all but the simplest library parts is a painful experience. Every time you hit 'New' you need to scroll to the bottom, then drag the thing to where it needs to be.
'New' could become 'Add' (goes to the bottom) and 'Insert' (working like in an Excel spreadsheet). Or even be replaced by 'Insert' alone.
And the parameter list box could have a horizontal split, again like Excel, so that you can simultaneously check and scroll two chunks of the parameter list. (This would make 'Insert' less of a desperate need, but I still think 'Insert' would be so much better than the current 'New'.)