SearchBar: Add Cancel button to stop long running tasks

Authored by loh.tar on Jan 20 2019, 12:32 PM.

Description

SearchBar: Add Cancel button to stop long running tasks

Summary:
Without this patch could it happens that Kate run an almost endless S&R
job which could lead up to an unusable system due to a run out of memory
with no possibility to cancel the job other than kill Kate, See...

CCBUG: 333517
CCBUG: 244424

Test Plan:
Before

New waiting for action

New while running job

Reviewers: KTextEditor, VDG, cullmann

Reviewed By: KTextEditor, cullmann

Subscribers: dhaumann, anthonyfieroni, brauch, cullmann, abetts, kwrite-devel, kde-frameworks-devel, KTextEditor

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D17459