I have 4 suggestions for constraints:
1. Add 'Flip Constraint' to right-click menu. When a part is constrained to another using 3 planes, and it needs to be flipped about one plane, (i.e. a bracket mounting on the opposite side of a part) it is very cumbersome to edit the constraints to do so. You either have to edit one, flip it, let the other fail, click through the design doctor error acceptance, then edit the second and flip it; or you have to suppress one, edit/flip the other, edit/flip the suppressed one, and unsuppress it. Wtih RMB option, you could highlight the two constraints and flip from the right click menu.
2. Separate the button to assume position/direction, so if I have 2 constraints already made, I can just make the 3rd mate with a zero offset and have it be in the correct direction. Too many times I'll be applying constraints to something I want without any offset, and either have to keep clicking/editing it to be 0, or end up with broken constraints because it doesn't flip correctly.
3. Double clicking a constraint in the tree should go straight to edit, not just entering a new dimension. That can already be done with a single click. RMB>navigate to the edit button often ends up in clicking an adjacent button by accident, such as "Drive"
4. Highlight the entire part rather than just the surface constrained. If the face is hidden it's sometimes hard to see what part it is unless you can see it directly, especially with a small part in a large assembly. Also, make the directional arrows easier to see without having to zoom out to infinity to know if it should be an aligned or flush mate.
