Explain why we use subprocess/QProcess.

qutebrowser/browser/curcommand.py

@@ -399,6 +399,10 @@ class CurCommandDispatcher(QObject):
         The command will be run in a shell, so you can use shell features like
         redirections.
 
+        We use subprocess rather than Qt's QProcess here because of it's
+        shell=True argument and because we really don't care about the process
+        anymore as soon as it's spawned.
+
         Args:
             cmd: The command to execute.
         """
@@ -409,7 +413,12 @@ class CurCommandDispatcher(QObject):
     @cmdutils.register(instance='mainwindow.tabs.cur', modes=['insert'],
                        name='open_editor', hide=True, needs_js=True)
     def editor(self):
-        """Open an external editor with the current form field."""
+        """Open an external editor with the current form field.
+
+        We use QProcess rather than subprocess here because it makes it a lot
+        easier to execute some code as soon as the process has been finished
+        and do everything async.
+        """
         frame = self._tabs.currentWidget().page_.currentFrame()
         elem = frame.findFirstElement(webelem.SELECTORS['editable_focused'])
         if elem.isNull():