The section on PtResourceRec_t resource records includes new mod_f special values (Pt_CHANGE_CANVAS and Pt_CHANGE_CANVAS_REDRAW) and a new arg_value type (Pt_ARG_IS_IMAGE).
Widget classes now include a textual description. See “Widget class resource table.”
PtContainerChildRedirect() no longer exists; use the Pt_SET_CHILD_REDIRECT_F manifest in your widget's class-creation function instead. See “Container widget anatomy.”

Creating a List Widget

The prototypes have changed for PtSuperClassGenListMouse() and PtSuperClassGenListSelect().

Creating a Tree Widget

When expanding an item, the Tree Item State method returns zero to permit the expansion, or a nonzero value to prevent it — PtGenTreeExpand() returns this value. When collapsing an item, the Tree Item State method returns a nonzero value if the item is destroyed, or zero if the item still exists — PtGenTreeCollapse() returns this value (the prototype has changed).
PtGenTreeAddAfter() and PtGenTreeAddFirst() now return 0 on success, or -1 if the item is already in a tree.
PtGenTreeFreeItems() now returns 0 on success, or -1 if the items are still in a tree.

Binding Widgets into PhAB

The method for binding widgets into PhAB has changed. If PhAB can open the shared object for your widget, it can display your widget correctly, and you can work with them “live.”

Widget Building Library API

New functions:

PtAnchorDeregister() — replaces PtContainerDeregister().
PtAnchorRegister() — replaces PtContainerRegister().
PtResizeCanvas() — similar to PtAttemptResize(), but easier to use.

PtContainerChildRedirect() no longer exists; use the Pt_SET_CHILD_REDIRECT_F manifest in your widget's class-creation function instead. See “Container widget anatomy” in the Anatomy of a Widget chapter.
PtGetAnchoredExtent() no longer exists; anchors are handled by the widget library.
PtInvokeResizeCallbacks() is now a void function. It assumes that the widget passed to it is a container.

Miscellaneous Widget-Building Tips

Various tips have been added.