Sometime it is really hard to spot where your sketch is unconstrained. All lines can be black, but can still be unconstrained. There have been cases where I had to give up and leave the sketch unconstrained, because I could simply not find where I had forgot to constrain it.
It would be great if the there was a "highlight unconstrained points" button, that would point out all unconstrained points/lines for example by flashing the area, or doing some really exaggerated coloring.
For example, the following simple sketch has two unconstrained points, but all lines are black. In this case it is pretty easy to find them, but when the sketch gets more complex they can be really hard to find.
In this example case, the highlight unconstrained points" button could for example do something like this, and maybe even flashing the red circles.
