[GUI] CGA Proposal

[Krasimir Angelov]

--- Axel Simon <simona_@web.de> wrote:
> Critics and comment appreciated,

The proposal is far from the real world. Here are my
objections:

  - The attribute appClass must be read only.
The GNOME library requires to know the application
name and version before initialization. That means
that the 'appClass' attribute in the proposal should
be readonly and its value should be set at startup.

   - The comments for 'appCreateToolbar' are:
-- | Specify whether to create a toolbar for this
window or not.
--
-- A toolbar is by default created (True) for each
document window (see
-- 'newDocumentApp') and not created (False) for
primary control windows
-- (see 'newControlApp').
This seems like mistake. The function defines a
property for application while in the same time it
manages a window. 
  Why not just leave the programmer to create a
toolbar if he/she needs it?

   - For the predefined menus there are defined
newFileMenu, newEditMenu, newViewMenu, newInfoMenu and
newWindowMenu functions. What they do? As I understand
the newFileMenu function creates an empty menu which
is named "File" and is placed at the appropriate
place. The programmer is responsible for the menu
content. Am I right? If this is true then why not
leave the programmer to create the menus like other
user defined menus? The creation of predefined menus
is required only if the application is document based.
If there aren't defined document types then the
library will never mount the predefined menus and the
programmer can create its own menus.

   - What is the meaning of the 'attrMenuName'?

   - The primary window is explicitly created. That
means that the application can have many primary
windows and each of them owns the menu bar. This is
possible under Windows and GNOME but is impossible
under MacOS where the menu bar owned from the
application. What will happen if the programmer
forgets to create the primary window and try to create
a menu bar? Under MacOS this is OK but under Windows
and GNOME this will cause runtime error. My proposal
is to have primary window only under Windows and
GNOME. The primary window is implicitly created and in
SDI and MDI mode it is owner of all windows (with
exception for dialogs and utility windows). In
controled SDI mode each window will be top level and
the primary window will own only the menu bar and the
utility windows. An example for application with
controled SDI interface under Windows is the Delphi
environment and the GIMP under Linux. The MacOS
application doesn't have a primary window because the
menu bar is owned from the application and all windows
there should be top level.

    - The newControlApp function should receive the
application name and version as arguments. In the
proposal doesn't have function for initialization. In
the GNOME it is necessary to call gnome_program_init
function before any call other call to GNOME. Under
Windows the function for initialization registers the
new window classes (RegisterClass from Win32 API).
After initialization it is necessary to run the main
event loop. Under GNOME the main loop is gtk_main()
and
under Windows this is GetMessage/DispathMessage loop.
The application finishes after the main loop finish.
As the final step the library should free all
resources allocated from the operating system. All
this is made from the 'start' function in HToolkit.
The application itself is implicitly created from the
start function. This prevents the programmer to call
the newControlApp (or similar function twice).

   - The appMDIHint attribute like the 'appClass'
should be readonly. The reason is that after the
application initialization it is hard or impossible to
change the application type.

   - The information provided with the DocumentApp is
not enough to manage the predefined File menu. 

PS: The prototype implementation for the Document and
DocumentTemplate types, announced in the specification
for HToolkit is available in CVS:

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/htoolkit/port/src/Port/Document.hs?rev=1.4&content-type=text/vnd.viewcvs-markup

Best regards,
Krasimir

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