The Header Option Buttons are the buttons that are available at the top of screen during all Path constructions.
They are more general than the side Option Buttons which differ from tool to tool. The first is the Lock Button.
Lock ButtonThe Lock Button freezes motion input. When the path is locked, no future touch events will change it until it’s unlocked again. This is useful, for instance, if you’re trying to precisely place a path, set an angle, position a bezier point or vertex, etc. because even lifting your finger from the page can generate a stray motion event that might change your carefully constructed path. The Lock Button will prevent that. Simply toggle it ON and a rotation, for example, is suddenly frozen. Use the Lock Button whenever you’re having trouble getting something just right. Also, one important thing to remember is that you’ll still be able to use the side Option Buttons when motion events are locked. This can be particularly useful if you want to see how other construction options would affect your Path but you don’t want to change the attribute (rotation, location, etc.) that you’ve already fixed in place.
Snapping ButtonSnapping is explained fully in the Snapping section. This button is where snapping is activated and its behavior defined. One of the things that makes constructing Paths easier in Doodleback is Snapping. This means that you can get close to a particular point and Doodleback will automatically snap to a nearby “important” point. This might be a vertex of a Polygon, a center of a Circle, an intersection point on a Grid, etc. However, since Paths exist in 3 dimensions, sometimes Doodleback can’t tell which important point you want to snap to. This button lets you prioritize snapping by top-most path, bottom-most path, or even by the age of the Path.
“Allow snapping by age” is an advanced option described in the Snapping section.
You can, of course, turn Snapping completely OFF here too.