how do you control line lock icon appearance?

[LanggamanXavierMassed]

 how do you control line lock icon appearance? i placed lines and when i adjust some, a lock icon appears but i cannot figure out how to show it because it doesn't appear in others, THANK YOU

[bin · Accepted solution]

It appears when:

1. draw the line onto an element, either end-points or the whole line.

2. drag the end-points or the whole line onto an element.

3. use Align command to lock the end-points or the whole line onto an element.

It also appears when it's locked onto something after you select it.

https://youtu.be/Yos1J7-K3KU