DragonFly On-Line Manual Pages
Tk_MaintainGeometry(3) Tk Library Procedures Tk_MaintainGeometry(3)
Tk_MaintainGeometry, Tk_UnmaintainGeometry - maintain geometry of one
window relative to another
Tk_MaintainGeometry(window, container, x, y, width, height)
Tk_Window window (in) Window whose geometry is to be
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
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
int width (in) Desired width for window, in pixels.
int height (in) Desired height for window, in pixels.
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
 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.
 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.
 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
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.
geometry manager, map, container, parent, position, window, unmap
Tk 4.0 Tk_MaintainGeometry(3)