The Perforce integration has an annoying bug since 5646 (on Windows XP):
When adding a new file to a project, a modal dialog opens which asks whether you want to add the newly created file to Perforce. At the same time, a progress bar window opens indicating the Perforce command progress.
Since 5646 unfortunately, the modal dialog window focus is lost (focus is on progress window which waits for the dialog to be closed) and can't be restored. All versions before kept the modal dialog focused.
The only possibility to resolve this issue so far is to terminate IDEA and restart it, which is no suitable option.