With this action you can get the colour being used for any shapes (rectangle/ellipse/line) or for any text that is drawn. The action will return the colour to the target variable that you specify, which can have been created previously or can be a new temporary one (if you check the "Temp" check-box).
The above action block get's the current draw colour and if it isn't set to $ffffff (white) it is set to that colour.