Provided by: tk8.6-doc_8.6.13-2_all 
NAME
Tk_MaintainGeometry, Tk_UnmaintainGeometry - maintain geometry of one window relative to
another
SYNOPSIS
#include <tk.h>
Tk_MaintainGeometry(window, container, x, y, width, height)
Tk_UnmaintainGeometry(window, container)
ARGUMENTS
Tk_Window window (in) Window whose geometry is to be controlled.
Tk_Window container (in) Window relative to which window's geometry will be
controlled.
int x (in) Desired x-coordinate of window in container, measured in
pixels from the inside of container's left border to the
outside of window's left border.
int y (in) Desired y-coordinate of window in container, measured in
pixels from the inside of container's top border to the
outside of window's top border.
int width (in) Desired width for window, in pixels.
int height (in) Desired height for window, in pixels.
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DESCRIPTION
Tk_MaintainGeometry and Tk_UnmaintainGeometry make it easier for geometry managers to deal
with windows whose containers are not their parents. Three problems arise if the
container for a window is not its parent:
[1] The x- and y-position of the window must be translated from the coordinate system
of the container to that of the parent before positioning the window.
[2] If the container window, or any of its ancestors up to the window's parent, is
moved, then the window must be repositioned within its parent in order to maintain
the correct position relative to the container.
[3] If the container or one of its ancestors is mapped or unmapped, then the window
must be mapped or unmapped to correspond.
None of these problems is an issue if the parent and container are the same. For example,
if the container or one of its ancestors is unmapped, the window is automatically removed
by the screen by X.
Tk_MaintainGeometry deals with these problems for windows whose containers are not their
parents, as well as handling the simpler case of windows whose container are their
parents. Tk_MaintainGeometry is typically called by a window manager once it has decided
where a window should be positioned relative to its container. Tk_MaintainGeometry
translates the coordinates to the coordinate system of window's parent and then moves and
resizes the window appropriately. Furthermore, it remembers the desired position and
creates event handlers to monitor the container and all of its ancestors up to (but not
including) the window's parent. If any of these windows is moved, mapped, or unmapped,
the window will be adjusted so that it is mapped only when the container is mapped and its
geometry relative to the container remains as specified by x, y, width, and height.
When a window manager relinquishes control over a window, or if it decides that it does
not want the window to appear on the screen under any conditions, it calls
Tk_UnmaintainGeometry. Tk_UnmaintainGeometry unmaps the window and cancels any previous
calls to Tk_MaintainGeometry for the container-window pair, so that the window's geometry
and mapped state are no longer maintained automatically. Tk_UnmaintainGeometry need not
be called by a geometry manager if the window, the container, or any of the container's
ancestors is destroyed: Tk will call it automatically.
If Tk_MaintainGeometry is called repeatedly for the same container-window pair, the
information from the most recent call supersedes any older information. If
Tk_UnmaintainGeometry is called for a container-window pair that is is not currently
managed, the call has no effect.
KEYWORDS
geometry manager, map, container, parent, position, window, unmap