#  Copyright (c) 1990 The Regents of the University of California.
#  Copyright (c) 1994-1996 Sun Microsystems, Inc.
#  See the file "license.terms" for information on usage and redistribution
#  of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
#  @(#) CrtWindow.c 1.21 96/11/01 09:42:20
#

=head1 NAME

Tk_CreateWindow, Tk_CreateWindowFromPath, Tk_DestroyWindow, Tk_MakeWindowExist - create or delete window

=for category C Programming

=head1 SYNOPSIS

B<#include E<lt>tk.hE<gt>>

Tk_Window
B<Tk_CreateWindow>(I<interp, parent, name, topLevScreen>)

Tk_Window
B<Tk_CreateWindowFromPath>(I<interp, tkwin, pathName, topLevScreen>)

B<Tk_DestroyWindow>(I<tkwin>)

B<Tk_MakeWindowExist>(I<tkwin>)

=head1 ARGUMENTS

=over 4

=item Tcl_Interp *interp (out)

Tcl interpreter to use for error reporting.  If no error occurs,
then I<*interp> isn't modified.

=item Tk_Window parent (in)

Token for the window that is to serve as the logical parent of
the new window.

=item char *name (in)

Name to use for this window.  Must be unique among all children of
the same I<parent>.

=item char *topLevScreen (in)

Has same format as I<screenName>.  If NULL, then new window is
created as an internal window.  If non-NULL, new window is created as
a top-level window on screen I<topLevScreen>.  If I<topLevScreen>
is an empty string (``'') then new
window is created as top-level window of I<parent>'s screen.

=item Tk_Window tkwin (in)

Token for window.

=item char *pathName (in)

Name of new window, specified as path name within application
(e.g. B<.a.b.c>).

=back

=head1 DESCRIPTION

The procedures B<Tk_CreateWindow>
and B<Tk_CreateWindowFromPath>
are used to create new windows for
use in Tk-based applications.  Each of the procedures returns a token
that can be used to manipulate the window in other calls to the Tk
library.  If the window couldn't be created successfully, then NULL
is returned and I<interp-E<gt>result> is modified to hold an error
message.

Tk supports two different kinds of windows:  internal
windows and top-level windows.
An internal window is an interior window of a Tk application, such as a
scrollbar or menu bar or button.  A top-level window is one that is
created as a child of a screen's root window, rather than as an
interior window, but which is logically part of some existing main
window.  Examples of top-level windows are pop-up menus and dialog boxes.

New windows may be created by calling
B<Tk_CreateWindow>.  If the I<topLevScreen> argument is
NULL, then the new window will be an internal window.  If
I<topLevScreen> is non-NULL, then the new window will be a
top-level window: I<topLevScreen> indicates the name of
a screen and the new window will be created as a child of the
root window of I<topLevScreen>.  In either case Tk will
consider the new window to be the logical child of I<parent>:
the new window's path name will reflect this fact, options may
be specified for the new window under this assumption, and so on.
The only difference is that new X window for a top-level window
will not be a child of I<parent>'s X window.  For example, a pull-down
menu's I<parent> would be the button-like window used to invoke it,
which would in turn be a child of the menu bar window.  A dialog box might
have the application's main window as its parent.

B<Tk_CreateWindowFromPath> offers an alternate way of specifying
new windows.  In B<Tk_CreateWindowFromPath> the new
window is specified with a token for any window in the target
application (I<tkwin>), plus a path name for the new window.
It produces the same effect as B<Tk_CreateWindow> and allows
both top-level and internal windows to be created, depending on
the value of I<topLevScreen>.  In calls to B<Tk_CreateWindowFromPath>,
as in calls to B<Tk_CreateWindow>, the parent of the new window
must exist at the time of the call, but the new window must not
already exist.

The window creation procedures don't
actually issue the command to X to create a window.
Instead, they create a local data structure associated with
the window and defer the creation of the X window.
The window will actually be created by the first call to
B<Tk_MapWindow>.  Deferred window creation allows various
aspects of the window (such as its size, background color,
etc.) to be modified after its creation without incurring
any overhead in the X server.  When the window is finally
mapped all of the window attributes can be set while creating
the window.

The value returned by a window-creation procedure is not the
X token for the window (it can't be, since X hasn't been
asked to create the window yet).  Instead, it is a token
for Tk's local data structure for the window.  Most
of the Tk library procedures take Tk_Window tokens, rather
than X identifiers.  The actual
X window identifier can be retrieved from the local
data structure using the B<Tk_WindowId> macro;  see
the manual entry for B<Tk_WindowId> for details.

B<Tk_DestroyWindow> deletes a window and all the data
structures associated with it, including any event handlers
created with B<Tk_CreateEventHandler>.  In addition,
B<Tk_DestroyWindow> will delete any children of I<tkwin>
recursively (where children are defined in the Tk sense, consisting
of all windows that were created with the given window as I<parent>).
If I<tkwin> was created by B<Tk_CreateInternalWindow> then event
handlers interested in destroy events
are invoked immediately.  If I<tkwin> is a top-level or main window,
then the event handlers will be invoked later, after X has seen
the request and returned an event for it.

If a window has been created
but hasn't been mapped, so no X window exists, it is
possible to force the creation of the X window by
calling B<Tk_MakeWindowExist>.  This procedure issues
the X commands to instantiate the window given by I<tkwin>.

=head1 KEYWORDS

create, deferred creation, destroy, display, internal window,
screen, top-level window, window