&|Purpose: | Embed context sensitive help into a Tcl/Tk application |&
&|See also:| [balloon help] |&
&|Credits: | [DKF]s  https://stackoverflow.com/questions/35576895/display-hint-of-any-widget-on-mouse-over-in-tcl-tk%|%answer to a respective question%|% on stack overflow.|&
&|Pros:    | As simple as can be, no external dependencies, no clutter, less distraction |&
&|Cons:    | Always needs space on the GUI, less obvious help for unexperienced users. |&

[LEG]
Instead of popping up an extra window for tooltip help:

   * Reserve some space on your GUI for displaying the respective help text. This can be a status line on the bottom  of the window.
   * Update this help text with the <Enter>/<Leave> events of the respective widgets.

Example code:

======
# a global variable, you might want to put this in a namespace
set help "Hover over any widget to get help for it"

proc help {widget text} {
    # register help text with widget

    bind $widget <Enter> +[list set ::help $text]
    bind $widget <Leave> +[list set ::help ""]
}

# create the help text widget somewhere on your applications top level
# window or in some frame $w

label $w.help -textvariable help -anchor nw -justify left

# register help for the help window itself
help $w.help "Hover over any widget to get help for it"
======

% in text gets substituted according to [bind] rules.
Use %% to get a simple percent sign.

Variable substitution in text is done in the moment the help text is 
registered. See [Bindings and variable substitution] for hints how to
change this.


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