Sketcher ConstrainLock

"Create a lock constraint on the selected item"

Description
This constraint tool attempts to fully constrain any selected item.

NOTE: It is advised that this tool be exclusively used on points for the time-being:

Owing to the fact that FreeCAD is still under development - this tool exhibits strange behaviour when it attempts to 'lock' anything other than a point. For example (as of V0.12 R4802), when locking a circle by its circumferential line rather than its centre point, a horizontal constraint and a vertical constraint appear in the constraints dialogue, but they are both of value zero and do not appear in the graphics window.

Usage

 * 1) Firstly it is necessary to highlight an item you wish to constrain. For reasons alluded-to above it is wise to only highlight a point.
 * 2) Highlighting of a drawing item is achieved by moving the mouse over the item and clicking the left-mouse-button.
 * 3) A highlighted item will change colour to green.
 * 4) Once an item is highlighted, left-clicking on the lock constraint serves to lock the highlighted item in-place. This usually manifests as two constraints: a horizontal distance constraint from the drawing axis origin, and a vertical constraint from the drawing axis origin.