Tk_MaintainGeometry(3) Tk Library Procedures Tk_MaintainGeometry(3)
Tk_MaintainGeometry, Tk_UnmaintainGeometry - maintain geometry of one window relative to
Tk_MaintainGeometry(slave, master, x, y, width, height)
Tk_Window slave (in) Window whose geometry is to be controlled.
Tk_Window master (in) Window relative to which slave's geometry will be con-
int x (in) Desired x-coordinate of slave in master, measured in pixels
from the inside of master's left border to the outside of
slave's left border.
int y (in) Desired y-coordinate of slave in master, measured in pixels
from the inside of master's top border to the outside of
slave's top border.
int width (in) Desired width for slave, in pixels.
int height (in) Desired height for slave, in pixels.
Tk_MaintainGeometry and Tk_UnmaintainGeometry make it easier for geometry managers to deal
with slaves whose masters are not their parents. Three problems arise if the master for a
slave is not its parent:
 The x- and y-position of the slave must be translated from the coordinate system of
the master to that of the parent before positioning the slave.
 If the master window, or any of its ancestors up to the slave's parent, is moved,
then the slave must be repositioned within its parent in order to maintain the cor-
rect position relative to the master.
 If the master or one of its ancestors is mapped or unmapped, then the slave must be
mapped or unmapped to correspond.
None of these problems is an issue if the parent and master are the same. For example, if
the master or one of its ancestors is unmapped, the slave is automatically removed by the
screen by X.
Tk_MaintainGeometry deals with these problems for slaves whose masters are not their par-
ents, as well as handling the simpler case of slaves whose masters are their parents.
Tk_MaintainGeometry is typically called by a window manager once it has decided where a
slave should be positioned relative to its master. Tk_MaintainGeometry translates the
coordinates to the coordinate system of slave's parent and then moves and resizes the
slave appropriately. Furthermore, it remembers the desired position and creates event
handlers to monitor the master and all of its ancestors up to (but not including) the
slave's parent. If any of these windows is moved, mapped, or unmapped, the slave will be
adjusted so that it is mapped only when the master is mapped and its geometry relative to
the master 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_Unmaintain-
Geometry. Tk_UnmaintainGeometry unmaps the window and cancels any previous calls to
Tk_MaintainGeometry for the master-slave pair, so that the slave's geometry and mapped
state are no longer maintained automatically. Tk_UnmaintainGeometry need not be called by
a geometry manager if the slave, the master, or any of the master's ancestors is
destroyed: Tk will call it automatically.
If Tk_MaintainGeometry is called repeatedly for the same master-slave pair, the informa-
tion from the most recent call supersedes any older information. If Tk_UnmaintainGeometry
is called for a master-slave pair that is is not currently managed, the call has no
geometry manager, map, master, parent, position, slave, unmap
Tk 4.0 Tk_MaintainGeometry(3)