Control for color seemingly accepts invalid value but ignores them

1. Create a new Qt Quick Application project.
2. Open its QML file in Design mode.
3. Select the Text item.
4. In the Properties view, change the value in the edit control for the "Text Color" to "#1 2 3" and press Enter. Use the "right" arrow key for the spaces.
5. Change the focus to a different control.
   The edit still displays "#1 2 3".
6. Save, close and reopen the QML file.
   The edit still displays "#1 2 3".

The Designer should not accept invalid values.