make AcceptingInputStatus work

Summary:
the culript seems the Qt::WindowDoesNotAcceptFocus flag,
removing it makes it possible to have back working text fields in the
panel

Test Plan: works with an ad-hoc applet, notes applet needs fixing

Reviewers: Plasma, KWin, davidedmundson

Reviewed By: Plasma, KWin, davidedmundson

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D21319