XML editor, XPath/XQuery editor, and output 'editor' are resizeable.
editor label on the top right corner slides to the right when the corresponding editor receives focus, hiding most of the label body to provide more room for editing.
format button on the bottom right corner goes translucent when the corresponding editor receives focus for similar reason.
XPath/XQuery dropdown might be implemented using 'Navigation' button -behaves similar to radio button- instead of using dropdown/combobox control. See below (capture from Flat UI)
Arrange the layout to be tidier