The IDE ignores SIGINT: the "Stop" button in run configurations may not work

This notification is displayed when the IDE (or one of its parent processes) was launched in such a way that blocks propagation of INT signal (SIGINT). The IDE sends that signal to a child process when a user clicks the "Stop" button in a run configuration toolbar; with the signal blocked, the action no longer works. The IDE itself is unable to undo the blocking, it's up to the user to change the way the IDE is launched so that the signal is not blocked (e.g. run from the terminal instead of the dmenu).

You can find more technical details in this comment.