Make auto-complete fill-in in "Attributes" window available

Idea created by prinz_martin on Nov 26, 2012
    When assigning attributes while editing to a selected feature you have the possibility to select attributes via the "Symbol Class Selector". To choose a symbol class with the mouse is IMHO a bit to time consuming. It would be nice to have this classes as basis for an auto-complete fill-in in the edited field! Then there is no Mouse necessary for semi-automatic filling in this field.