#2119 [text yview] shows strange behaviour

[Marcel Broeken]

[$text yview] returns two fractions. When using the
first fraction in [$text yview moveto $fraction] I
would expect the fractions returned by [$text yview]
after this moveto to be the same as before the moveto.
Most of the time this is the case.

Using [$text yview] with Tcl 8.5a4 on Windows shows
some strange behaviour. The fractions before and after
a moveto call are the same, except when the contents of
the text widget are deleted and insert in between the
first [$text yview] and [$text yview moveto $fraction],
even if the contents stay the same.

I've added an example script to show this bug. [test]
shows some output without deleting and replacing the
contents and [test true] shows the output with deleting
and replacing the contents. Notice the difference! I
think this bug might be related to #1499165.

[Marcel Broeken]

Example script to show strange behaviour