Sketcher ConstrainCoincident

"Create a coincident constraint on the selected item"

Description
This constraint tool takes two points as its argument and serves to make the two points coincident. (Meaning to make them as-one-point.)

In practical terms this constraint tool is useful when there is a break in a profile for example - where two lines end near each other and need to be joined - a coincident constraint on their end-points will close the gap.

Usage
As stated above, this tool takes two arguments - both are points. NOTE: In order to make two points coincident, FreeCAD must necessarily move one, or both, of the original points.
 * 1) Firstly it is necessary to highlight two distinct points. (Note this will not work if, for example, you attempt to select the start and end point of the same line).
 * 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) Subsequent items can be highlighted by repeating the above procedure(s) NOTE: There is no-need to hold-down any special key like Ctrl to achieve multiple item selection in a drawing.
 * 5) Once you have two points highlighted, left-clicking on the 'PointOnPoint' constraint will cause the two points to become coincident and be replaced by a single point.