title: How to verify whether a shortcut-keysequence is valid?
body: <p>In my application I allow the user to enter shortcuts in a line-edit.  E.g., if the user enters <kbd>Ctrl</kbd> + <kbd>F10</kbd>, this means that a certain action will be executed if the user presses <kbd>F10</kbd>.</p>
  
  <p>I use the QKeySequence class to convert the string <kbd>Ctrl</kbd> + <kbd>F10</kbd> to a QKeySequence, and then pass this QKeySequence to the QShortCut's constructor.</p>
  
  <p>Is there a way to verify that the QKeySequence is valid for a shortcut?  E.g. if the user enters <kbd>Ctrl</kbd> + <kbd>Shift</kbd>, this is converted to a QKeySequence, but I don't want to allow this for a shortcut.
  Same with strings like <kbd>Ctrl</kbd> + <kbd>F10</kbd> + <kbd>Ctrl</kbd> (which becomes <kbd>Ctrl</kbd>), ...</p>