When adding new points or moving existing points the sketching software helps the user by snapping lines / points to align with existing points on the sketch.
Snap to Sensitivity setting
Clicking on the close sketch and selecting "Settings" displays a popup that shows the Snap To Sensitivity distances settings.
The Snap To Sensitivity can be toggled on and off using the Tick Box
If the Tick Box is ticked then Snap to is in use, otherwise no snap to features are enabled.
Each of the 4 Snap to Sensitivity distances can be changed independently.
The Snap to Sensitivity status controls the background colour of the Snap To Button in the 3 rulers. If Snap To is not in use, the background of the button is set to Red, otherwise it is set to black.
Snao To is in use
Snao To not in Use
Adding new points
When adding new points the line being created will snap to Vertical / Horizontal / 45 degrees if it is within the Snap To Sensitivity distance or vertical / Horizontal or 45 degrees
Adding the first point of a new room
When adding the first point of a new room, if the point is close to the corner of a room, it will be placed at that corner. If the new point is close to a line it will placed at the nearest point on the line.
Closing an existing room
When adjusting a line length, if the end point of the line is within the Snap To Sensitivity distance then the room will be automatically closed.
Move Vertex
When moving an existing vertex the highlighted line being moved will snap to Vertical / Horizontal / 45 degrees if it is within the Snap To Sensitivity distance or vertical / Horizontal or 45 degrees