Sometimes while sketching I am unable to trim a line without
eliminating some pertinent dimensions/constraints. I try using the
split entities command and then switch the unwanted portion to a
construction line. However, when I then try to do an extrusion I
always get a message box telling me that I have open contour. Is
this a glitch or am I not using the command correctly?
You might try sketching points and dimensioning to them if a change needs made.