gh-143754: Modernize Tkinter docs (GH-143841)

Use more relevant terminology instead of "master"/"slave" widgets where possible.
(cherry picked from commit 813fc7a)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Author: serhiy-storchaka

Doc/library/tkinter.rst

@@ -175,12 +175,12 @@ the modern themed widget set and API::
    .. attribute:: master
 
       The widget object that contains this widget.  For :class:`Tk`, the
-      *master* is :const:`None` because it is the main window.  The terms
+      :attr:`!master` is :const:`None` because it is the main window.  The terms
       *master* and *parent* are similar and sometimes used interchangeably
       as argument names; however, calling :meth:`winfo_parent` returns a
-      string of the widget name whereas :attr:`master` returns the object.
+      string of the widget name whereas :attr:`!master` returns the object.
       *parent*/*child* reflects the tree-like relationship while
-      *master*/*slave* reflects the container structure.
+      *master* (or *container*)/*content* reflects the container structure.
 
    .. attribute:: children
 
@@ -636,15 +636,15 @@ The Packer
 .. index:: single: packing (widgets)
 
 The packer is one of Tk's geometry-management mechanisms.    Geometry managers
-are used to specify the relative positioning of widgets within their container -
-their mutual *master*.  In contrast to the more cumbersome *placer* (which is
+are used to specify the relative positioning of widgets within their container.
+In contrast to the more cumbersome *placer* (which is
 used less commonly, and we do not cover here), the packer takes qualitative
 relationship specification - *above*, *to the left of*, *filling*, etc - and
 works everything out to determine the exact placement coordinates for you.
 
-The size of any *master* widget is determined by the size of the "slave widgets"
-inside.  The packer is used to control where slave widgets appear inside the
-master into which they are packed.  You can pack widgets into frames, and frames
+The size of any container widget is determined by the size of the "content widgets"
+inside.  The packer is used to control where content widgets appear inside the
+container into which they are packed.  You can pack widgets into frames, and frames
 into other frames, in order to achieve the kind of layout you desire.
 Additionally, the arrangement is dynamically adjusted to accommodate incremental
 changes to the configuration, once it is packed.
@@ -671,7 +671,7 @@ For more extensive information on the packer and the options that it can take,
 see the man pages and page 183 of John Ousterhout's book.
 
 anchor
-   Anchor type.  Denotes where the packer is to place each slave in its parcel.
+   Anchor type.  Denotes where the packer is to place each content in its parcel.
 
 expand
    Boolean, ``0`` or ``1``.
@@ -680,10 +680,10 @@ fill
    Legal values: ``'x'``, ``'y'``, ``'both'``, ``'none'``.
 
 ipadx and ipady
-   A distance - designating internal padding on each side of the slave widget.
+   A distance - designating internal padding on each side of the content.
 
 padx and pady
-   A distance - designating external padding on each side of the slave widget.
+   A distance - designating external padding on each side of the content.
 
 side
    Legal values are: ``'left'``, ``'right'``, ``'top'``, ``'bottom'``.
@@ -756,8 +756,8 @@ subclassed from the :class:`Wm` class, and so can call the :class:`Wm` methods
 directly.
 
 To get at the toplevel window that contains a given widget, you can often just
-refer to the widget's master.  Of course if the widget has been packed inside of
-a frame, the master won't represent a toplevel window.  To get at the toplevel
+refer to the widget's :attr:`master`.  Of course if the widget has been packed inside of
+a frame, the :attr:`!master` won't represent a toplevel window.  To get at the toplevel
 window that contains an arbitrary widget, you can call the :meth:`_root` method.
 This method begins with an underscore to denote the fact that this function is
 part of the implementation, and not an interface to Tk functionality.

Lib/tkinter/__init__.py

@@ -1852,15 +1852,15 @@ def __repr__(self):
         return '<%s.%s object %s>' % (
             self.__class__.__module__, self.__class__.__qualname__, self._w)
 
-    # Pack methods that apply to the master
+    # Pack methods that apply to the container widget
     _noarg_ = ['_noarg_']
 
     def pack_propagate(self, flag=_noarg_):
         """Set or get the status for propagation of geometry information.
 
-        A boolean argument specifies whether the geometry information
-        of the slaves will determine the size of this widget. If no argument
-        is given the current setting will be returned.
+        A boolean argument specifies whether the size of this container will
+        be determined by the geometry information of its content.
+        If no argument is given the current setting will be returned.
         """
         if flag is Misc._noarg_:
             return self._getboolean(self.tk.call(
@@ -1871,28 +1871,28 @@ def pack_propagate(self, flag=_noarg_):
     propagate = pack_propagate
 
     def pack_slaves(self):
-        """Return a list of all slaves of this widget
-        in its packing order."""
+        """Returns a list of all of the content widgets in the packing order
+        for this container."""
         return [self._nametowidget(x) for x in
                 self.tk.splitlist(
                    self.tk.call('pack', 'slaves', self._w))]
 
     slaves = pack_slaves
 
-    # Place method that applies to the master
+    # Place method that applies to the container widget
     def place_slaves(self):
-        """Return a list of all slaves of this widget
-        in its packing order."""
+        """Returns a list of all the content widgets for which this widget is
+        the container."""
         return [self._nametowidget(x) for x in
                 self.tk.splitlist(
                    self.tk.call(
                        'place', 'slaves', self._w))]
 
-    # Grid methods that apply to the master
+    # Grid methods that apply to the container widget
 
     def grid_anchor(self, anchor=None): # new in Tk 8.5
         """The anchor value controls how to place the grid within the
-        master when no row/column has any weight.
+        container widget when no row/column has any weight.
 
         The default anchor is nw."""
         self.tk.call('grid', 'anchor', self._w, anchor)
@@ -1909,7 +1909,7 @@ def grid_bbox(self, column=None, row=None, col2=None, row2=None):
         starts at that cell.
 
         The returned integers specify the offset of the upper left
-        corner in the master widget and the width and height.
+        corner in the container widget and the width and height.
         """
         args = ('grid', 'bbox', self._w)
         if column is not None and row is not None:
@@ -1967,7 +1967,7 @@ def grid_columnconfigure(self, index, cnf={}, **kw):
 
     def grid_location(self, x, y):
         """Return a tuple of column and row which identify the cell
-        at which the pixel at position X and Y inside the master
+        at which the pixel at position X and Y inside the container
         widget is located."""
         return self._getints(
             self.tk.call(
@@ -1976,9 +1976,9 @@ def grid_location(self, x, y):
     def grid_propagate(self, flag=_noarg_):
         """Set or get the status for propagation of geometry information.
 
-        A boolean argument specifies whether the geometry information
-        of the slaves will determine the size of this widget. If no argument
-        is given, the current setting will be returned.
+        A boolean argument specifies whether the size of this container will
+        be determined by the geometry information of its content.
+        If no argument is given the current setting will be returned.
         """
         if flag is Misc._noarg_:
             return self._getboolean(self.tk.call(
@@ -2004,8 +2004,13 @@ def grid_size(self):
     size = grid_size
 
     def grid_slaves(self, row=None, column=None):
-        """Return a list of all slaves of this widget
-        in its packing order."""
+        """Returns a list of the content widgets.
+
+        If no arguments are supplied, a list of all of the content in this
+        container widget is returned, most recently managed first.
+        If ROW or COLUMN is specified, only the content in the row or
+        column is returned.
+        """
         args = ()
         if row is not None:
             args = args + ('-row', row)
@@ -2591,8 +2596,8 @@ def pack_configure(self, cnf={}, **kw):
         before=widget - pack it before you will pack widget
         expand=bool - expand widget if parent size grows
         fill=NONE or X or Y or BOTH - fill widget if widget grows
-        in=master - use master to contain this widget
-        in_=master - see 'in' option description
+        in=container - use the container widget to contain this widget
+        in_=container - see 'in' option description
         ipadx=amount - add internal padding in x direction
         ipady=amount - add internal padding in y direction
         padx=amount - add padding in x direction
@@ -2631,25 +2636,31 @@ class Place:
 
     def place_configure(self, cnf={}, **kw):
         """Place a widget in the parent widget. Use as options:
-        in=master - master relative to which the widget is placed
-        in_=master - see 'in' option description
-        x=amount - locate anchor of this widget at position x of master
-        y=amount - locate anchor of this widget at position y of master
+        in=container - the container widget relative to which this widget is
+                       placed
+        in_=container - see 'in' option description
+        x=amount - locate anchor of this widget at position x of the
+                   container widget
+        y=amount - locate anchor of this widget at position y of the
+                   container widget
         relx=amount - locate anchor of this widget between 0.0 and 1.0
-                      relative to width of master (1.0 is right edge)
+                      relative to width of the container widget (1.0 is
+                       right edge)
         rely=amount - locate anchor of this widget between 0.0 and 1.0
-                      relative to height of master (1.0 is bottom edge)
-        anchor=NSEW (or subset) - position anchor according to given direction
+                      relative to height of the container widget (1.0 is
+                      bottom edge)
+        anchor=NSEW (or subset) - position anchor according to given
+                                  direction
         width=amount - width of this widget in pixel
         height=amount - height of this widget in pixel
         relwidth=amount - width of this widget between 0.0 and 1.0
-                          relative to width of master (1.0 is the same width
-                          as the master)
+                          relative to width of the container widget (1.0 is
+                          the same width as the container widget)
         relheight=amount - height of this widget between 0.0 and 1.0
-                           relative to height of master (1.0 is the same
-                           height as the master)
+                           relative to height of the container widget (1.0
+                           is the same height as the container widget)
         bordermode="inside" or "outside" - whether to take border width of
-                                           master widget into account
+                                           the container widget into account
         """
         self.tk.call(
               ('place', 'configure', self._w)
@@ -2685,8 +2696,8 @@ def grid_configure(self, cnf={}, **kw):
         """Position a widget in the parent widget in a grid. Use as options:
         column=number - use cell identified with given column (starting with 0)
         columnspan=number - this widget will span several columns
-        in=master - use master to contain this widget
-        in_=master - see 'in' option description
+        in=container - use the container widget to contain this widget
+        in_=container - see 'in' option description
         ipadx=amount - add internal padding in x direction
         ipady=amount - add internal padding in y direction
         padx=amount - add padding in x direction