QApplication instance

[marcel]

But it is not clear what are you're trying to do...
Why are you starting an event loop in a plugin?
The plugin should use the host applciation's event loop, not create its own.

Ant what's with the thread?

[nile.one]

in the example i get error
ASSERT failure in QWidget: "Widgets must be created in the GUI thread."

So, what's the solution? not to implement GUI in thread or what?
But if i want to implement plugin's GUI in independent thread in case of not blocking the application while long-time work of plugin.

[nile.one]

ok, finally i got it working. i've chosen the solution to run the Qt GUI not in independent thread, i'll use the threads only in core classes.