If an application is started through Qt Creator 2 (no Debugging) a small red rectangle is enabled to stop the application. After a while Qt Creator ask for "Force Stop" because the application is not responding (happens with a simple Qt Console application). But even if I handle all possible Linux signals, I'm unable to gracefully quit the application. Does anyone now what happens behinde the scenes when the button is pressed (I was unable to see anything usefull through strace)?