PIKA UI Framework
  =================

This document describes how the PIKA UI framework functions and is
implemented. Here, "UI framework" refers to the system that saves the
UI layout between PIKA sessions, i.e. how docks, dockable dialogs etc
are setup.


  Key Classes
  -----------

PikaDockable      - Represents a dockable dialog.
PikaDockbook      - A GtkNotebook of PikaDockables
PikaDock          - A columns of PikaDockbooks
PikaToolbox       - Subclasses PikaDock, contains the toolbox.
                    Dockables are added at the bottom
PikaMenuDock      - Subclasses PikaDock, contains dockables, should
                    probably be merged with PikaDock. The name
                    contains "menu" from the time when it hosted the
                    Image Selection Menu that is now in the
                    PikaDockWindow
PikaDockColumns   - A set of PikaDocks arranged side by side.
PikaDockWindow    - A toplevel window containing a PikaDockColumns.
PikaImageWindow   - A toplevel window containing images and one
                    PikaDockColumns to the left and to the right.
PikaDialogFactory - A factory to create and position toplevel windows
PikaSessionInfo   - Contains session info for one toplevel
PikaUIConfigurer  - Configures the UI when switching between
                    single-window and multi-window mode


  PikaDialogFactory
  -----------------

The PikaDialogFactory can be considered to solve two distinct
problems:

1. Create widgets from text, in particular from text in sessionrc
2. Session manage toplevel windows so their position is remembered
   across PIKA sessions

One possible design adjustment would be to have PikaWidgetFactory that
takes care of 1), and then have PikaDialogFactory inherit from
GtkWidgetFactory and implementing 2). PikaWidgetFactory could possibly
use GtkBuilder.


  sessionrc
  ---------
When PIKA starts, the sessionrc file is parsed. This step puts
PikaSessionInfo:s into PikaDialogFactories. Later when dialogs are
created, the dialog factory looks up existing session info entries. If
one exists, it uses the session info to set e.g. the position of the
created dialog. If it doesn't exist, it creates a new session info
object for the dialog. When PIKA exists, the current session infos are
then written back to sessionrc.