How to appropriately use ctkPluginFrameworkLauncher::stop()

[alundilong]

Dear CTK Developer,
I am facing a strange problem as I quit a GUI app. I believe it is related to multiple threads. Here is a snapshot of the main function where the ctkPluginFramework is initialized. To test if all plugin could be removed once the stop function is called, a line is added as follows,

The body of stop function is as follows,

Here is a snapshot of what occur, with this I believe it is a multiple thread issue. I would like to take some advice on how(or where) to use ctkPluginFrameworkLauncher::stop(). Thanks!