When the profile was to small, it would switch into empty state
and clear the plot info.
On resize events, the plot info is not recalculated.
This means that when making the profile extremely small and
then bigger, nothing is shown.
This may also happen on startup. The profile is rendered into
a 0x0 widget and then gets a resize event.
Therefore, remember when the profile is empty and force a
recalculation of the plot info.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
9bca38afcf