Robert Lancaster authored Nov 29, 2018 and Jasem Mutlaq committed Nov 29, 2018

Summary:
Fixing an intermittent crash caused by QCustomPlot's replot method
being used in a concurrent thread  The reason for it is because Qt does not
support painting to GUI elements in any thread but the GUI thread and
QCustomPlot's replot method includes a repaint.  So if the Histogram is
currently visible and construct histogram is run in a concurrent thread,
the program would call replot and crash.

Reviewers: mutlaqja

Reviewed By: mutlaqja

Subscribers: kde-edu

Tags: #kde_edu

Differential Revision: https://phabricator.kde.org/D17228