Oxygen XML Editor Author allows you to declare some elements to be foldable (collapsible). This is especially useful when working with large documents organized in logical blocks, editing a large DocBook article or book for instance. Oxygen XML Editor marks the foldable content with a small blue triangle. When you hover with your mouse pointer over this marker, a dotted line borders the collapsible content. The following contextual actions are available:
Close Other
FoldsCtrl NumPad/ (Command NumPad/ on OS
X) -
Folds all the elements except the current element. 
Collapse Child Folds
(Ctrl+Decimal) - Folds the elements indented with one
level inside the current element.-
Expand Child Folds (Ctrl+Equals)- Unfolds all child elements of the currently
selected element. -
Expand
All (Ctrl+NumPad+*) - Unfolds all elements in the current
document. -
Toggle Fold - Toggles the state of the current
fold.
To define the element whose content can be folded by the user, you must use the property:
-oxy-foldable:true;. To define the elements that are folded by default, use
the -oxy-folded:true property.
Note: The -oxy-folded property
works in conjunction with the -oxy-foldable property. Thus, the
folded property is ignored if the -oxy-foldable property
is not set on the same element.
When collapsing an element, it is useful to keep some of its content visible, like a short
description of the collapsed region. The property -oxy-not-foldable-child is
used to identify the child element that is kept visible. It accepts as value an element name
or a list of comma separated element names. The first child element from the XML document that
appears in the list of element names will be identified as the not foldable child and
displayed. If the element is marked as foldable (-oxy-foldable:true;)
but it doesn't have the property -oxy-not-foldable-child or none of the
specified non-foldable children exists, then the element is still foldable. In this case the
element kept visible when folded will be the before
pseudo-element.
Note: Deprecated properties foldable,
not-foldable-child, and folded are also
supported.
Folding DocBook Elements
All the elements below can have a title child element and are considered to be logical sections. You mark them as being foldable leaving the title element visible.
set,
book,
part,
reference,
chapter,
preface,
article,
sect1,
sect2,
sect3,
sect4,
section,
appendix,
figure,
example,
table {
-oxy-foldable:true;
-oxy-not-foldable-child: title;
}