Set the label to expand, so it actually fills
the width that we allocated for it, instead
of shrinking back to the minimum width for
its height.
Fixes: #5521
Setting max-width-chars to the number of characters
in the string works ok only as long as the average
char width we get from Pango matches reality. Sadly
that seems not always the case, and this code was
causing short Chinese tooltips to always be broken
into two lines.
Fixes: #4470
We don't want wrapping labels to cause tooltips to
have excessive height, so we need to set a reasonable
value for width-chars, without forcing short tooltips
into a full line length. Also be careful to respect
preexisting line breaks (we have such examples in
widget factory).
The position child property is problematic, since it
requires us to emit notification for all children when
inserting a child early in the list of children.
Remove the property from all ui files.
It's not a hugely complicated file, but it's easier to deal with some of
the details of tooltip windows styling if we have a UI file to edit,
instead of source code.
