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'\" Copyright (c) 1992 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
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.TH tk n 8.4 Tk "Tk Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
tk \- Manipulate Tk internal state
.SH SYNOPSIS
\fBtk\fR \fIoption \fR?\fIarg ...\fR?
.BE
.SH DESCRIPTION
.PP
The \fBtk\fR command provides access to miscellaneous
elements of Tk's internal state.
Most of the information manipulated by this command pertains to the
application as a whole, or to a screen or display, rather than to a
particular window.
The command can take any of a number of different forms
depending on the \fIoption\fR argument.  The legal forms are:
.TP
\fBtk appname \fR?\fInewName\fR?
.
If \fInewName\fR is not specified, this command returns the name
of the application (the name that may be used in \fBsend\fR
commands to communicate with the application).
If \fInewName\fR is specified, then the name of the application
is changed to \fInewName\fR.
If the given name is already in use, then a suffix of the form
.QW "\fB #2\fR"
or
.QW "\fB #3\fR"
is appended in order to make the name unique.
The command's result is the name actually chosen.
\fInewName\fR should not start with a capital letter.
This will interfere with option processing, since names starting with
capitals are assumed to be classes;  as a result, Tk may not
be able to find some options for the application.
If sends have been disabled by deleting the \fBsend\fR command,
this command will reenable them and recreate the \fBsend\fR
command.
.TP
\fBtk busy \fIsubcommand\fR ...
.
This command controls the marking of window hierarchies as
.QW busy ,
rendering them non-interactive while some other operation is proceeding. For
more details see the \fBbusy\fR manual page.
.TP
\fBtk caret \fIwindow \fR?\fB\-x \fIx\fR? ?\fB\-y \fIy\fR? ?\fB\-height \fIheight\fR?
.
Sets and queries the caret location for the display of the specified
Tk window \fIwindow\fR.  The caret is the per-display cursor location
used for indicating global focus (e.g. to comply with Microsoft
Accessibility guidelines), as well as for location of the over-the-spot
XIM (X Input Methods) or Windows IME windows.  If no options are specified,
the last values used for setting the caret are return in option-value pair
format.  \fB\-x\fR and \fB\-y\fR represent window-relative coordinates, and
\fB\-height\fR is the height of the current cursor location, or the height
of the specified \fIwindow\fR if none is given.
.TP
\fBtk inactive \fR?\fB\-displayof \fIwindow\fR? ?\fBreset\fR?
.
Returns a positive integer, the number of milliseconds since the last
time the user interacted with the system. If the \fB\-displayof\fR
option is given then the return value refers to the display of
\fIwindow\fR; otherwise it refers to the display of the application's
main window.
.RS
.PP
\fBtk inactive\fR will return \-1, if querying the user inactive time
is not supported by the system, and in safe interpreters.
.PP
If the literal string \fBreset\fR is given as an additional argument,
the timer is reset and an empty string is returned. Resetting the
inactivity time is forbidden in safe interpreters and will throw an
error if tried.
.RE
.TP
\fBtk fontchooser \fIsubcommand\fR ...
Controls the Tk font selection dialog. For more details see the
\fBfontchooser\fR manual page.
.TP
\fBtk scaling \fR?\fB\-displayof \fIwindow\fR? ?\fInumber\fR?
.
Sets and queries the current scaling factor used by Tk to convert between
physical units (for example, points, inches, or millimeters) and pixels.  The
\fInumber\fR argument is a floating point number that specifies the number of
pixels per point on \fIwindow\fR's display.  If the \fIwindow\fR argument is
omitted, it defaults to the main window.  If the \fInumber\fR argument is
omitted, the current value of the scaling factor is returned.
.RS
.PP
A
.QW point
is a unit of measurement equal to 1/72 inch.  A scaling factor
of 1.0 corresponds to 1 pixel per point, which is equivalent to a standard
72 dpi monitor.  A scaling factor of 1.25 would mean 1.25 pixels per point,
which is the setting for a 90 dpi monitor; setting the scaling factor to
1.25 on a 72 dpi monitor would cause everything in the application to be
displayed 1.25 times as large as normal.  The initial value for the scaling
factor is set when the application starts, based on properties of the
installed monitor, but it can be changed at any time.  Measurements made
after the scaling factor is changed will use the new scaling factor, but it
is undefined whether existing widgets will resize themselves dynamically to
accommodate the new scaling factor.
.RE
.TP
\fBtk useinputmethods \fR?\fB\-displayof \fIwindow\fR? ?\fIboolean\fR?
.
Sets and queries the state of whether Tk should use XIM (X Input Methods)
for filtering events.  The resulting state is returned.  XIM is used in
some locales (i.e., Japanese, Korean), to handle special input devices. This
feature is only significant on X.  If XIM support is not available, this
will always return 0.  If the \fIwindow\fR argument is omitted, it defaults
to the main window.  If the \fIboolean\fR argument is omitted, the current
state is returned.  This is turned on by default for the main display.
.TP
\fBtk windowingsystem\fR
.
Returns the current Tk windowing system, one of
\fBx11\fR (X11-based), \fBwin32\fR (MS Windows),
or \fBaqua\fR (Mac OS X Aqua).
.SH "SEE ALSO"
busy(n), fontchooser(n), send(n), winfo(n)
.SH KEYWORDS
application name, send
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