Rhino WIP Feature: Grasshopper 2 Script Components

I see how this was pretty confusing. In the latest update all borders use Rhino.UI.ThemeSettings.Frame.Edge:

Meaning we get borders with 3, 2, and 1 pixels widths when collapsing the left panel:

IMO this looks weird/unintentional, especially when using a darker color like here. Which could be fixed by using Rhino.UI.ThemeSettings.Content.Background for the two 2 pixel wide interior borders (i.e. similar to the horisontal interior border in the previous release):

(:see_no_evil_monkey:)