Patch from David Fries

The existing comment was

// Try to keep the dialog small and non-obtrusive.
but it prevented the user form making it even smaller.
Make the minimum size smaller than the initial size, and enable
options to take less space for it be even smaller.

Reviewers: mlaurent, dvratil

Reviewed By: dvratil

Subscribers: dvratil, kde-pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org//D16244