Tk_CreateWindow(3) Tk Library Procedures Tk_CreateWindow(3)
Tk_CreateWindow, Tk_CreateWindowFromPath, Tk_DestroyWindow, Tk_MakeWindowExist - create or
Tk_CreateWindow(interp, parent, name, topLevScreen)
Tk_CreateAnonymousWindow(interp, parent, topLevScreen)
Tk_CreateWindowFromPath(interp, tkwin, pathName, topLevScreen)
Tcl_Interp *interp (out) Tcl interpreter to use for error reporting. If no
error occurs, then *interp is not modified.
Tk_Window parent (in) Token for the window that is to serve as the logi-
cal parent of the new window.
const char *name (in) Name to use for this window. Must be unique among
all children of the same parent.
const char *topLevScreen (in) Has same format as 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 topLevScreen. If topLevScreen is an
empty string ("") then new window is created as
top-level window of parent's screen.
Tk_Window tkwin (in) Token for window.
const char *pathName (in) Name of new window, specified as path name within
application (e.g. .a.b.c).
The procedures Tk_CreateWindow, Tk_CreateAnonymousWindow, and 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 could not be created successfully, then NULL is returned and
interp->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 win-
dow, 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 Tk_CreateWindow. If the topLevScreen argument is
NULL, then the new window will be an internal window. If topLevScreen is non-NULL, then
the new window will be a top-level window: topLevScreen indicates the name of a screen and
the new window will be created as a child of the root window of topLevScreen. In either
case Tk will consider the new window to be the logical child of 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 parent's X window. For example, a pull-down menu's 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.
Tk_CreateAnonymousWindow differs from Tk_CreateWindow in that it creates an unnamed win-
dow. This window will be manipulable only using C interfaces, and will not be visible to
Tcl scripts. Both interior windows and top-level windows may be created with Tk_Cre-
Tk_CreateWindowFromPath offers an alternate way of specifying new windows. In Tk_Cre-
ateWindowFromPath the new window is specified with a token for any window in the target
application (tkwin), plus a path name for the new window. It produces the same effect as
Tk_CreateWindow and allows both top-level and internal windows to be created, depending on
the value of topLevScreen. In calls to Tk_CreateWindowFromPath, as in calls to Tk_Cre-
ateWindow, 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 do not actually issue the command to X to create a window.
Instead, they create a local data structure associated with the window and defer the cre-
ation of the X window. The window will actually be created by the first call to Tk_Map-
Window. 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
cannot be, since X has not 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 Tk_WindowId macro; see the manual entry
for Tk_WindowId for details.
Tk_DestroyWindow deletes a window and all the data structures associated with it, includ-
ing any event handlers created with Tk_CreateEventHandler. In addition, Tk_DestroyWindow
will delete any children of tkwin recursively (where children are defined in the Tk sense,
consisting of all windows that were created with the given window as parent). If tkwin is
an internal window, then event handlers interested in destroy events are invoked immedi-
ately. If 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 has not been mapped, so no X window exists, it is possi-
ble to force the creation of the X window by calling Tk_MakeWindowExist. This procedure
issues the X commands to instantiate the window given by tkwin.
create, deferred creation, destroy, display, internal window, screen, top-level window,
Tk 4.2 Tk_CreateWindow(3)