deliberately changed the behaviour of Enter/Leave events of widgets in a
parent/child relationship: now when entering a child, the parent gets a
leave event.

This however kills tooltips on the parent, which previously (up to tk
8.6.12) worked on both, parent *and* child.

This has an impact on megawidgets which have a
parent-child-relationship: previously (before tcl 8.6.13) a tooltip
worked on all parts of the megawidget, now (tcl 8.6.13 and later) the
situation is more complex:

<pre>
wm geometry . 200x100
# a "mega-widget" with borders
pack [frame .f -bg green1] -side top
pack [frame .f.f1 -bg red -width 20 -height 20] -side left -padx 10 -pady 10
pack [label .f.lbl -bg white -text label-1] -side right

# a "mega-widget" without borders (no padding)
pack [frame .f2 -bg green1] -side bottom
pack [frame .f2.f1 -bg red -width 20] -side left -fill both
pack [label .f2.lbl -bg white -text label-2] -side right -fill both -expand yes

package require tooltip
tooltip::tooltip .f "This is .f"
tooltip::tooltip .f2 "This is .f2"
</pre>

In the upper "mega-widget", the tooltip comes and goes as the mouse
enters the various parts (red box, white label).

In the lower "mega-widget", the container itself is not visible, and
the tooltip works on all parts of the mega-widget.

IMHO the tooltip also needs to work on all parts in the upper
"mega-widget".

Proposed patch attached (ignore the <Leave> event if the event detail
is "NotifyInferior").

R'