contraint glyphs 2010

[omnifold]

I cant find where to turn on the glyph that when you draw a line a glyph indicating that a sketch constraint is being placed. Its the one that would disappear when you go on an angle.

 

[mcgyvr]

I believe you are looking for one of these 2 buttons..For the 2010 Ribbon UI. (being in an active sketch) Look in the Constraint section to the left of all the constraint buttons. "Constraint Inferrence" and "Constraint Persistance"