I’ve created a sketch that has a line on the bottom, then a spline connected to both ends. The spline forms a loop so the entire sketch forms a connected outline.

The line is supposed to be horizontal, but somehow it got tilted. When I try to hit the line with the Horizontal constraint, it moves the line only and not the connected spline.

I eventually got my sketch rotated by asking for the angle the line made with horizontal, selected the whole sketch, then rotated by minus the given angle. But I would really like to be able to do this with constraints.

I would love to “lock” the spline points relative to the line, or simply lock all points in a connected shape, so that when the line is moved by the constraint engine, the whole shape/sketch follows without deforming. In other words, I want to treat the sketch as a two-dimensonal rigid body whose position and angle can be adjusted by constraints. Can this be accomplished?

I am not sure what you mean. “Exit Sketching” was @0:45 but the video goes on to complete the move to @1:34. Please check again. What else do you want to do?
Tony