/**

 \page page_main_window Main Application Window

 \tableofcontents

 \image html main_window.png "Main Application Window"
 \image latex main_window.png "Main Application Window" width=5cm

 A FLUID project is a hierarchy of nodes. Each node holds information to
 generate C++ source code which in turn generates the user interface that
 is created in the layout editor windows. Projects usually define one or more
 functions. These functions can generate one or more
 FLTK windows and all the widgets that go inside those windows.

 The FLUID Main Window is split into three parts. The title bar shows the
 status of the source and project files. The menu bar provides a wealth of
 menu items for all major actions in FLUID. The biggest part of the
 app window is the widget browser, a tree structure that lists every code
 node and widget in the project.

 <!-- ---------------------------------------------------------------------- -->
 \section main_titlebar Title Bar

 \image html main_titlebar.png
 \image latex main_titlebar.png "Title Bar" width=5cm

 The title bar shows the status of the project file, _function_panel.fl_ in this
 case, followed by an asterisk if the project was changed after it was saved.
 If the asterisk shows, FLUID will ask the user to save changes before closing
 the project, loading another project, or starting a new one. Pressing `Ctrl-S`
 will save the project and make the asterisk disappear.

 The _.cxx_ in the title bar reflects the status of header and source files
 in relation to the project. A trailing asterisk indicates that the project and code
 files differ. Pressing `Ctrl-Shift-C` to write the code files will make this
 asterisk go away.

 \note FLUID currently supports only one open project at a time.

 <!-- ---------------------------------------------------------------------- -->
 \section main_menubar Application Menu Bar

 \image html main_menubar.png
 \image latex main_menubar.png "Main Menu" width=5cm

 The menu bar is the true control center of FLUID. All actions start here.

 The *File* menu offers the common file operation for FLUID projects. Projects
 can be loaded, merged, and saved. *Print* will print a snapshot of all open
 project windows.
 The *New From Template* item opens a dialog that provides access to a small
 number of sample projects. More projects can be added using *Save as Template*.

 Use *Write Code* to write the header and source code files, and *Write Strings*
 to write the translation file if one of the internationalization options
 is active.

 The *Edit* menu is mainly used to manipulate widgets within the widget tree.
 The bottom entries toggle various dialogs and pop up the settings panel.

 The *New* menu holds a list of all widgets that can be used in FLUID. They
 are grouped by functionality, very similarly to the widget bin. New widgets are
 added inside or right after the selected widget. If the parent widget is not
 compatible, FLUID tries to find another location for the widget. If that also
 fails, FLUID will pop up a dialog, describing the required parent type.

 The *Layout* menu is used to adjust the position and size of widgets in
 relation to each other.

 The *Shell* menu gives quick access to user definable shell scripts. Note that
 scripts can be stored inside `.fl` project files.

 \see \ref main_menu_items

 <!-- ---------------------------------------------------------------------- -->
 \section main_widget_browser Widget Tree View

 \image html main_browser.png
 \image latex main_browser.png "Widget Browser" width=5cm

 Widgets are stored in a hierarchy. You can open and close a level by clicking
 the "triangle" at the left of a widget. The leftmost widgets are the
 \e parents, and all the widgets listed below them are their \e children.
 Parents don't have to have any children.

 The top level of the hierarchy is composed of \e functions and
 \e classes. Each of these will produce a single C++ public function
 or class in the output <tt>.cxx</tt> file. Calling the function or
 instantiating the class will create all of the child widgets.

 The second level of the hierarchy contains the \e windows.
 Each of these produces an instance of class Fl_Window.

 Below that are either \e widgets (subclasses of Fl_Widget) or
 \e groups of widgets (including other groups). Plain groups are for
 layout, navigation, and resize purposes. <i>Tab groups</i> provide the
 well-known file-card tab interface.

 Widgets are shown in the browser by either their \e name (such
 as "Button emergency_btn" in the example), or by their \e type
 and \e label (such as "Double_Window "My Main Window"").

 You \e select widgets by clicking on their names, which highlights
 them (you can also select widgets from any displayed window). You can
 select many widgets by dragging the mouse across them, or by using
 Shift+Click to toggle them on and off. To select no widgets, click in
 the blank area under the last widget. Note that hidden children may
 be selected even when there is no visual indication of this.

 You \e open widgets by double-clicking on them, or (to open several
 widgets you have picked) by typing the F1 key. A control panel will appear
 so you can change the widget(s).

 Nodes are moved within their group using
 `F2` and `F3`. They can be grouped and ungrouped with `F7` and `F8`, and
 relocated by selecting them and using cut, copy, and paste.

 Every line in the browser has the same basic format. The level of indentation
 reflects the depth of a node within the tree.

 The triangle appears only in front of nodes that can have children. If it is
 white, the group has no children. If it is black, there is at least one child.
 If the triangle points to the right, the children are hidden in the tree view.
 Click the triangle to reveal all children.

 The icon to the right is a small representation of the base type of the node.
 Widgets are gray, windows have a blue title bar, and functional nodes are
 green. If the widget is static or private, a padlock icon will appear in the
 bottom right corner of the type icon.

 The content of text fields depends on the node type. If a comment is set, it
 appears in green over the text. Widgets combine their type (bold black) and
 label text (red), or their C++ name in black (not bold).

 All colors and font styles can be customized in the User tab of the
 Settings panel.

 <!-- ---------------------------------------------------------------------- -->
 \section main_menu_items The Main Menu

The "New" menu of the main menu bar is duplicated as a pop-up menu on any
layout editor window. The shortcuts for all the menu items work in any
window. The menu items are:

__File > New (Ctrl+n)__: Close the current project and start a new, empty project.

__File > Open... (Ctrl+o)__: Discard the current editing session and read in a
different `.fl` project file. You are asked for confirmation if you have
changed the current file.

FLUID can also read `.fd` files produced by the Forms and XForms "fdesign"
programs. It is best to _File > Merge_ them instead of opening them. FLUID does
not understand everything in a `.fd` file, and will print a warning message on
the controlling terminal for all data it does not understand. You will probably
need to edit the resulting setup to fix these errors. Be careful not to save
the file without changing the name, as FLUID will write over the `.fd` file
with its own format, which fdesign cannot read!

__File > Insert... (Ctrl+i)__: Insert the contents of another `.fl` file
without changing the name of the current `.fl` file. All the functions (even if
they have the same names as the current ones) are added, and you will have to
use cut/paste to put the widgets where you want.

__File > Save (Ctrl+s)__: Write the current data to the `.fl` file. If the
file is unnamed then FLUID will ask for a filename.

__File > Save As... (Ctrl+Shift+S)__: Ask for a new filename and
save the file.

__File > Save A Copy...__: Save a copy of the `.fl` data to a different file.

__File > Revert...__: Revert the `.fl` data to the previously saved state.

__File > New From Template...__: Create a new user interface design from a
previously saved template. This can be useful for including a predefined
enterprise copyright message for projects, or for managing boilerplate code
for repeating project code.

__File > Save As Template...__: Save the current project as a starting point
for future projects.

__File > Print... (Ctrl-P)__: Generate a printout containing all currently
open windows within your project.

__File > Write Code (Ctrl+Shift+C)__: Write the GUI layout as a `.cxx` and
`.h` file. These are exactly the same as the files you get when you run
FLUID with the `-c` switch.

The output file names are the same as the `.fl` file, with the leading directory
and trailing ".fl" stripped, and ".h" or ".cxx" appended.

__File > Write Strings (Ctrl+Shift+W)__: Write a message file for all of the
text labels and tooltips defined in the current file.

The output file name is the same as the `.fl` file, with the leading directory
and trailing ".fl" stripped, and ".txt", ".po", or ".msg" appended depending on
the \ref setting_i18n "Internationalization Mode".

__File > Quit (Ctrl+q)__: Exit FLUID. You are asked for confirmation if you
have changed the current file.

__Edit > Undo (Ctrl+z)__ and __Redo (Shift+Ctrl+z)__: FLUID saves the project
state for undo and redo operations after every major change.

__Edit > Cut (Ctrl+x)__: Delete the selected widgets and all of their children.
These are saved to a "clipboard" file and can be pasted back into any
FLUID window.

__Edit > Copy (Ctrl+c)__: Copy the selected widgets and all of their children
to the "clipboard" file.

__Edit > Paste (Ctrl+v)__: Paste the widgets from the clipboard file.

If the widget is a window, it is added to whatever function
is selected, or contained in the current selection.

If the widget is a normal widget, it is added to whatever
window or group is selected. If none is, it is added to the
window or group that is the parent of the current selection.

To avoid confusion, it is best to select exactly one widget
before doing a paste.

Cut/paste is the only way to change the parent of a
widget.

__Edit > Duplicate (Ctrl-u)__: Duplicate all currently selected widgets and
insert the duplicates after the last selected widget.

__Edit > Delete__: Delete all selected widgets.

__Edit > Select All (Ctrl+a)__: Select all widgets in the same group as the
current selection.

If they are all selected already then this selects all
widgets in that group's parent. Repeatedly typing `Ctrl+a` will
select larger and larger groups of widgets until everything is
selected.

__Edit > Properties... (F1 or double click)__: Display the current widget in
the widgets panel. If the widget is a window and it is not visible then the
window is shown instead.

__Edit > Sort__: Sort the selected widgets into left to right, top to bottom
order. You need to do this to make navigation keys in FLTK work correctly.
You may then fine-tune the sorting with "Earlier" and "Later". This does not
affect the positions of windows or functions.

__Edit > Earlier (F2)__: Move all of the selected widgets one earlier in order
among the children of their parent (if possible). This will affect navigation
order, and if the widgets overlap it will affect how they draw, as the later
widget is drawn on top of the earlier one. You can also use this to reorder
functions, classes, and windows within functions.

__Edit > Later (F3)__: Move all of the selected widgets one later in order
among the children of their parent (if possible).

__Edit > Group (F7)__: Create a new Fl_Group and make all the currently
selected widgets children of it.

__Edit > Ungroup (F8)__: Delete the parent group if all the children of a
group are selected.

__Edit > Show or Hide Overlays (Ctrl+Shift+O)__: Toggle the display of the
red overlays off, without changing the selection. This makes it easier to see
box borders and how the layout looks. The overlays will be forced back on if
you change the selection.

__Edit > Show or Hide Guides (Ctrl+Shift+G)__: Guides can be used to arrange a
widget layout easily and consistently. They indicate preferred widget
positions and sizes with user definable margins, grids, and gap sizes. See
the "Layout" tab in the "Settings" dialog, \ref setting_layout.

This menu item enables and disables guides and the snapping action when dragging
widgets and their borders.

__Edit > Show or Hide Restricted (Ctrl+Shift+R)__: The behavior of overlapping
widgets in FLTK is undefined. By activating this button, a hatch pattern is
shown, highlighting areas where restricted or undefined behavior may occur.

__Edit > Show or Hide Widget Bin (Alt+B)__: The widget bin provides quick
access to all widget types supported by FLUID. Layouts can be created by
clicking on elements in the widget bin, or by dragging them from the bin to
their position within the layout. This button shows or hides the widget bin.

__Edit > Show or Hide Code View (Alt+C)__: Shows or hide
the source code preview window. Any changes to the layout or code in the layout
editor can be previewed and verified immediately in the Code View window.

__Edit > Settings... (Alt+p)__: Open the application and project settings
dialog: \ref page_setting_dialog

__New > Code > Function__: Create a new C function. You will be asked for a
name for the function. This name should be a legal C++ function
template, without the return type. You can pass arguments which
can be referred to by code you type into the individual widgets.

If the function contains any unnamed windows, it will be
declared as returning an Fl_Window pointer. The unnamed window
will be returned from it (more than one unnamed window is
useless). If the function contains only named windows, it will
be declared as returning nothing (\c void ).

It is possible to make the <tt>.cxx</tt> output be a
self-contained program that can be compiled and executed. This
is done by deleting the function name so
\p main(argc,argv) is used. The function will call
\p show() on all the windows it creates and then call
\p Fl::run(). This can also be used to test resize
behavior or other parts of the user interface.

You can change the function name by double-clicking on the
function.

\see \ref functional_function

__New > Group > Window__: Create a new Fl_Window widget. The window is added
to the currently selected function, or to the function containing the currently
selected item. The window will appear, sized to 480x320. You can resize it to
whatever size you require.

The widget panel will also appear and is described later in
this chapter.

__New > ...__: All other items on the New menu are subclasses of
`Fl_Widget`. Creating them will add them to the
currently selected group or window, or the group or window
containing the currently selected widget. The initial
dimensions and position are chosen by copying the current
widget, if possible.

When you create the widget you will get the widget's control
panel, which is described later in this chapter.

__Layout > Align > ...__: Align all selected widgets to the first widget in
the selection.

__Layout > Space Evenly > ...__: Space all selected widgets evenly inside the
selected space. Widgets will be sorted from first to last.

__Layout > Make Same Size > ...__: Make all selected widgets the same size as
the first selected widget.

__Layout > Center in Group > ...__: Center all selected widgets relative to
their parent widget

__Layout > Grid and Size Settings... (Ctrl+g)__: Display the grid settings
panel. See \ref setting_layout .

This panel controls dimensions that all widgets snap to when you move
and resize them, and for the "snap" which is how far a widget has to be
dragged from its original position to actually change.

Layout preferences are defined using margins to parent groups and windows, gaps
between widget, and/or by overlaying a grid over a group or window. A layout
comes as a suite of three presets, one for the main application window, one
for dialog boxes, and one for toolboxes.

FLUID comes with two included layout suites. `FLTK` was used to design FLUID and
other included apps, and `Grid` is a more rigid grid layout. Users can add
more suites, import and export them, and include them into their `.fl`
project files.

__Shell > Customize... (Alt+x)__: Displays the shell command settings panel.
Shell commands are commonly used to run a 'make' script to compile the FLUID
output. See \ref setting_shell .

__Help > About FLUID__: Pops up a panel showing the version of FLUID.

*/
