JBoss Developer Studio comes with an XSD Editor for XML Schema files. This editor comes from the Web Tools Project (WTP) (see WTP Getting Started).
To create a new XSD file, right-click a folder in the Package Explorer view, select New > Other... from the context menu and then select XML > XML Schema in the dialog box.
The XSD Editor includes two viewers for working on the file, a Design viewer and a Source viewer:
In the Design viewer, you can drill down on an element by double-clicking on it:
Various edit options are available when you right-click an element in the diagram:
You can also use the Properties view to edit a selected element:
You can also use a Source viewer for the file. In this viewer, along with direct editing of the source code, you can also edit the file by using the Properties view on the right: