D12592: KFileWidget: Prevent places panel width from growing 1px iteratively

[Henrik Fehlauer]

rkflx added a dependent revision: D12593: KFileWidget: Save places panel width 
also after hiding panel.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D12592

To: rkflx, #frameworks
Cc: michaelh, bruns