Return window related information.

http://www.purl.org/tcl/home/man/tcl8.4/TkCmd/winfo.html

See [wm] for [Window manager] related information.

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   * '''winfo atom''' ''?-displayof window? name''
   * '''winfo atomname''' ''?-displayof window? id''
   * '''winfo cells''' ''window''
   * '''winfo children''' ''window''
   * '''winfo class''' ''window''
   * '''winfo colormapfull''' ''window''
   * '''winfo containing''' ''?-displayof window? rootX rootY''
   * '''winfo depth''' ''window''
   * '''winfo exists''' ''window''
   * '''winfo fpixels''' ''window number''
   * '''winfo geometry''' ''window''
   * '''winfo height''' ''window''
   * '''[winfo id]''' ''window''
   * '''winfo interps''' ''?-displayof window?''
   * '''winfo ismapped''' ''window''
   * '''winfo manager''' ''window''
   * '''winfo name''' ''window''
   * '''winfo parent''' ''window''
   * '''winfo pathname''' ''?-displayof window? id''
   * '''winfo pixels''' ''window number''
   * '''winfo pointerx''' ''window''
   * '''winfo pointerxy''' ''window''
   * '''winfo pointery''' ''window''
   * '''winfo reqheight''' ''window''
   * '''winfo reqwidth''' ''window''
   * '''[winfo rgb]''' ''window color''
   * '''winfo rootx''' ''window''
   * '''winfo rooty''' ''window''
   * '''winfo screen''' ''window''
   * '''winfo screencells''' ''window''
   * '''winfo screendepth''' ''window''
   * '''winfo screenheight''' ''window''
   * '''winfo screenmmheight''' ''window''
   * '''winfo screenmmwidth''' ''window''
   * '''winfo screenvisual''' ''window''
   * '''winfo screenwidth''' ''window''
   * '''winfo server''' ''window''
   * '''winfo toplevel''' ''window''
   * '''winfo viewable''' ''window''
   * '''winfo visual''' ''window''
   * '''winfo visualid''' ''window''
   * '''winfo visualsavailable''' ''window ?includeids?''
   * '''winfo vrootheight''' ''window''
   * '''winfo vrootwidth''' ''window''
   * '''winfo vrootx''' ''window''
   * '''winfo vrooty''' ''window''
   * '''winfo width''' ''window''
   * '''winfo x''' ''window''
   * '''winfo y''' ''window''

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Notice that the return value of [[winfo id ...]] is the id used
by [toplevel] and [wish] in
    toplevel ... -use $id
and
    wish ... -use $id

Here's an example:
    label .t1 -text Above
    label .t2 -text Below
    frame .holder -container 1
    pack .t1 .holder .t2
    exec wish other_application.tcl -use [winfo id .holder] &

[[Include an image here.]]

Incidental remark:  when [CL] substitutes
    exec tclkit tiny.tcl -use [winfo id .holder] &
for that last line, while running on WinNT, with tiny.tcl having content
    pack [.button -text "Push me" -command exit]
everything comes up OK.  When the button is pushed, "Dr. Watson"
appears.  Dismissing it eventually results in a whited-out frame
"hole" in the embedding Wish.  Is this an error in TclKit 8.4a3?

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It's probably time to make separate pages for "winfo atom", "winfo exists", "winfo id", and so on.

In any case, note that "winfo rgb" is ''not'' idempotent (or surjective) over the space of decimal triples.  [CL]
believes that the point is that the range space of "winfo rgb" is the display's color palette
(is that the right GUI vernacular?), and
is thus smaller than the full cartesian product ([[0-65535]],[[0-65535]],[[0-65535]]) one might
otherwise expect.

This presented with [VNC] service for which 
    winfo rgb . #ffff1fffffff
is 
    65535 0 65535
rather than the
    65535 7967 65535
delivered by a better-endowed display.

A start to a work-around for this is ...

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