Pick Lines
Functionality: Using a segment of a line object or an edge of a polygon object to generate auxiliary lines (objects will be snapped to the auxiliary lines during vector manipulation, ensuring precise and orderly arrangement).
Steps
1.Click on the Pick Lines 
button in the Vector Editor. Use the left mouse button to click on a segment of a line object or an edge of a polygon object to generate an auxiliary line. See the example below:
Selecting Auxiliary Lines
Note:
- During vector manipulation using auxiliary lines, you can set the buffer distance for snapping objects to the auxiliary lines and consider the Z value in the buffer distance calculation. See the example below:
Setting Snap Buffer