XML resources file format
                      ===============================
                      
 1. Basics
-----------

XML resource is well-formed XML document, i.e. all tags are paired
and there is only one root node, which is always <resource>.

In the following text, I will use standard XML terminology:

<tag_one prop1="prop" prop2='yes'>
   <tag_two/>
</tag_one>

Here, tag_one is a node (the word 'tag' refers to the type of the node),
prop1 and prop2 are properties and tag_two is a child node of tag_one.
Property's default value is the value that will be assigned to the property
if you do not specify it explicitly.

I will use the term "primary node" to refer to nodes than represent controls,
dialogs etc. "Secondary nodes" are nodes used to store data: 

<dialog name="my_dlg">                primary
  <title>Demo Dialog...</title>       secondary
  <size>100,200d</size>               secondary
  <children>                          secondary
    <button name="wxID_OK">           primary
      <label>Ok</label>               secondary
      <pos>10,10d</pos>               secondary
    </button>
  </children>
</dialog>

In the example above, <label>, <pos>, <size> and <title> are "variables",
i.e. they contain a value and not a list of children (unlike <children> node).

Any node (but the root one) may have property "platform" with possible 
values "unix", "win", "mac" or "os2". All nodes with "platform" property
specified and other than the platform the program is currently being executed
on will be removed when reading XML resource file.

Root node may have children of these and only these types: <menu>, <menubar>,
<dialog>, <panel>



 2. IDs
--------

Any primary node may have property "name" used to identify it. Default value
is "-1", any string is legal name. Names 
    wxID_OPEN, wxID_CLOSE, wxID_NEW,
    wxID_SAVE, wxID_SAVEAS, wxID_REVERT, 
    wxID_EXIT, wxID_UNDO, wxID_REDO,
    wxID_HELP, wxID_PRINT, wxID_PRINT_SETUP, 
    wxID_PREVIEW, wxID_ABOUT, wxID_HELP_CONTENTS,
    wxID_HELP_COMMANDS, wxID_HELP_PROCEDURES,
    wxID_CUT, wxID_COPY, wxID_PASTE,
    wxID_CLEAR, wxID_FIND, wxID_DUPLICATE,
    wxID_SELECTALL, wxID_OK, wxID_CANCEL,
    wxID_APPLY, wxID_YES, wxID_NO,
    wxID_STATIC, wxID_FORWARD, wxID_BACKWARD,
    wxID_DEFAULT, wxID_MORE, wxID_SETUP,
    wxID_RESET, wxID_HELP_CONTEXT
are translated into corresponding wxWindows ID constant, XMLID macro is used
otherwise to generate unique ID. wxWindows control created from named node
will have name=name and id=XMLID(name) or wxID_XXXX.


 3. Common variables types
--------------------------- 

Variables are always of a known type:

bool       - boolean value. "1", "true", "t", "on" mean TRUE, anything
             else (namely "0", "false", "f", "off") means FALSE.
             FIXME: maybe use only 1/0 ??
             
integer    - integer value, i.e. digits 0-9 plus optional minus sign.
             
text       - anything. Within text node all occurences of $ are replaced 
             by & (used for shortcuts, e.g. "E&xit"), $$ by $, \\, \n, \r,
             \t as usual in C++.

style      - (also called flags) list of flags delimined by any combination 
             of spaces and | characters. Resources parser accepts only 
             _registered_ flags -- i.e. flags that are valid for given 
             node/control. Example:
                  <flag>wxEXPAND | wxTOP|wxBOTTOM</flag>
                  
color      - color in HTML format: #rrggbb where rr,gg,bb are hexadecimal 
             values (00-FF) for red, green and blue components in 
             the RGB color model
             
coord      - size or position information. Consists of two integers
             separated by comma ("x,y"). The values are in pixels 
             unless "d" is attached to the right side of it -- 
             in which case the values are interpreted as dialog units.
             Value of -1 means "use default". Examples: 
                  30,30
                  -1,-1
                  50,-1
                  145,56d
                  67,-1d



 4. Layout
----------- 

Most common nodes layout is as follows:

<primary_node name="name" platform="platform">
    <var_1>...</var_1>
    .
    .
    .
    <var_n>...</var_n>
    <children>
        (n primary nodes)
    </children>
</primary_node>

where children node is supported only by panels, dialogs etc. -- see 
nodes description for details.

In the following text, 

   TYPE var_name [ (= default_value) ]
   
means that given primary node may have child node with name var_name
and content type TYPE. If default value is given, the node is optional
and default_value will be used if not specified. Otherwise, the node
is mandatory and must always be present. For example, "color fg" means
than variable tag fg, e.g. <fg>#rr0000</fg> is expected.



 5. Common controls variables
------------------------------

_All_ nodes that represent wxWindows controls (gauge, panel, dialog, 
textctrl etc.) accept the following properties:

coord   pos       (= -1,-1) position of the control. Default value 
                  equals to wxDefaultPosition
coord   size      (= -1,-1) size of the control. Default value equals to 
                  wxDefaultSize
text    tooltip   window's tooltip
color   bg        background color of the control
color   fg        foreground/text color of the control
style   style     control style flag. Default value is 
                  control-dependent (but 0 is common value)
style   exstyle   control extended style flag
bool    enabled   (= 1) is the control enabled?
bool    hidden    (= 0) is the control hidden?
bool    focused   (= 0) has the control focus?


_Usually_ (but not always, only when it makes sense) controls support text
variable label which contains displayed text and/or value which contains
editable text. These are always explicitly mentioned in tag description.




 6. Tags description
---------------------

If 'Control' is derived from wxControl, it supports all variables from '5.'
'Styles' section lists all acceptable flags for style and exstyle variables.


 <panel>
--------- 
      Control:
         wxPanel

      Variables:
         only common controls variables

      Styles:
         wxNO_3D, wxTAB_TRAVERSAL, wxWS_EX_VALIDATE_RECURSIVELY



 <dialog>
----------
      Control:
         wxDialog

      Variables:
         style    style     (= wxDEFAULT_DIALOG_style)
         text     title     dialog's title         

      Styles:
         wxSTAY_ON_TOP, wxCAPTION, wxDEFAULT_DIALOG_style, wxTHICK_FRAME,
         wxSYSTEM_MENU, wxRESIZE_BORDER, wxRESIZE_BOX, wxDIALOG_MODAL,
         wxDIALOG_MODELESS, wxNO_3D, wxTAB_TRAVERSAL, 
         wxWS_EX_VALIDATE_RECURSIVELY



 <boxsizer>
--------------
      Control:
         wxBoxSizer (not a control)

      Behaviour:
         boxsizer's parent must be either <panel>, <dialog> or another
         sizer, nothing else!
         
         If the sizer does not have parent sizer, the sizer will attach itself
         to the parent panel/dialog using SetAutoLayout(TRUE) and SetSizer().
         If the parent panel/dialog has default size (i.e. not specified in
         the resource), the sizer will fit it using wxSizer::Fit(). If the
         parent panel/dialog is resizable, size hints will be set 
         automatically.

      Variables:
         style    orient    (= wxHORIZONTAL) orientation, either 
                            wxHORIZONTAL or wxVERTICAL

      Styles:
         wxHORIZONTAL, wxVERTICAL (for orient variable)

         wxLEFT, wxRIGHT, wxTOP, wxBOTTOM, wxNORTH, wxSOUTH, wxEAST, wxWEST,
         wxALL, wxGROW, wxEXPAND, wxSHAPED, wxSTRETCH_NOT, wxALIGN_CENTER,
         wxALIGN_CENTRE, wxALIGN_LEFT, wxALIGN_TOP, wxALIGN_RIGHT, 
         wxALIGN_BOTTOM, wxALIGN_CENTER_HORIZONTAL, wxALIGN_CENTRE_HORIZONTAL,
         wxALIGN_CENTER_HORIZONTAL, wxALIGN_CENTRE_HORIZONTAL (for flag
         variable of <item> or <spacer> child nodes)

      Child nodes:
         Contains child node <children> which has arbitrary number of
         <sizeritem> and <spacer> child nodes.
         
          <sizeritem>
         -------------
            Variables:
               integer  option    (= 0) relative size of the widget
               style    flag      (= 0) style flag
               integer  border    (= 0) surrounding border
               
            Has exactly one child node <window> that contains the control
            (or child sizer because sizers may be nested) 
            to be inserted into the sizer.

          <spacer>
         ----------
            Variables:
               integer  option    (= 0) relative size of the widget
               style    flag      (= 0) style flag
               integer  border    (= 0) surrounding border

            Inserts empty space into the sizer
            


 <staticboxsizer>
------------------
      Control:
         wxStaticBoxSizer (not a control)

      Same as <boxsizer> except that it has additional variable:
      
               text     label     (= "") label of surrounding static box

      wxStaticBox required by wxStaticBoxSizer is created automatically!



 <notebooksizer>
-----------------
      Control:
         wxNotebookSizer (not a control)

      Behaviour:
         notebooksizer's parent must be a sizer (not notebooksizer,
         see below)!

      Variables:
         none

      Styles:
         none

      Child nodes:
         Has exactly one child node <window> that contains the notebook
         (nothing else is allowed!) to be inserted into the sizer.



 <textctrl>
------------ 
      Control:
         wxTextCtrl

      Variables:
         text     value     (= "")default text of the control

      Styles:
         wxTE_PROCESS_ENTER, wxTE_PROCESS_TAB, wxTE_MULTILINE, wxTE_PASSWORD,
         wxTE_READONLY, wxHSCROLL



 <htmlwindow>
--------------
      Control:
         wxHtmlWindow

      Variables:
         integer  borders   (= 0) window's borders 
                            (see wxHtmlWindow::SetBorders)
         text     url       (= "") if present, given page will be loaded
         text     htmlcode  (= "") if present, given _text_ will be displayed                            
                            (you will have to use CDATA section
                            to embed HTML code into XML document)

      Styles:
         wxHW_SCROLLBAR_NEVER, wxHW_SCROLLBAR_AUTO