A deterministic end result when timer is stop

[houmingc]

i have a LED blinking red and black toggling between the two color.
When timer stop, the LED appears to be sometimes black, sometimes red.

I resort to cast the LED red again after timer stop, but the results is still the same.
I thought this is because time taken to stop the timer is longer compared to the time taken to execute next instruction subsequently, thus a delay is needed

Now sloution is using qWait and qSleep and if there is other solution.

QTest::qSleep(100); // no event processing
QTest::qWait(100); // event processing