Translations:Tutorial custom placing of windows and doors/26/en

From FreeCAD Documentation

9. Draw a fancy sketch containing three closed wires. Make sure to provide constraints to all wires.

9.1. The outside wire is the biggest one, and will define the main dimensions of the window object, and the size of the hole created when it's embedded in an Arch Wall. Make sure the dimensions are named appropriately, for example, Width and Height. A constraint also defines the curvature of the outer wire; give it an appropriate name, like HeightCurve.
9.2. The second wire is offset from the outer wire, and together with it, they define the width of the fixed frame of the window. Name the offset appropriately, for example, FrameFixedOffset. It will be used for both the top vertical and horizontal offsets. The bottom offset, if set to zero, will result in the fixed frame touching the bottom of the window; this can be used to model a door instead of a window. Give it an appropriate name, like FrameFixedBottom.
9.3. The third, innermost wire is offset from the second wire, and together with it, they define the frame of the window that can open. The innermost wire also defines the size of the glass panel. Again, give meaningful names to these offsets, for example, FrameInnerOffset and FrameInnerBottom.
9.4. In order to build succesfully the sketch, use horizontal (Sketcher ConstrainHorizontal) and vertical (Sketcher ConstrainVertical) constraints for the straight sides; use auxiliary construction geometry (Sketcher ToggleConstruction), and tangential constraints (Sketcher ConstrainTangent) to correctly place the circular arcs at the top. As in this case the window is symmetrical, consider equality (Sketcher ConstrainEqual), symmetrical (Sketcher ConstrainSymmetric), and point on object (Sketcher ConstrainPointOnObject) constraints where it makes sense.