In Impress and Draw, you can connect each two shapes with a line called a connector. When you draw a connector between shapes, the connector will be attached to a glue point on each shape. Each shape has some default glue points, and the positions of the default glue points depend on the specific shape. You can add your own custom glue points to a shape and then attach connectors to the custom glue points.
Do one of the following to get existing glue points visible for all elements:
Click the Glue Points icon on the Drawing toolbar; or
Click the Insert Glue Point icon on the Glue Points toolbar.
Select element on slide where you want to add glue points.
Click inside the shape where you want to add the new glue point.
If the shape is filled, you can click anywhere inside the shape. If the shape is unfilled, you can click the border to insert a glue point. Once inserted, you can drag the glue point to another position inside the shape.
With the four icons next to the Insert Glue Point icon, you choose the directions which will be permitted for a connector at this glue point. You can choose one or more directions for a particular glue point.
If the Glue Point Relative icon is active, the glue point moves when you resize the object to keep its position relative to the object borders.
If the Glue Point Relative icon is not active, the icons next to it are no longer greyed out. With these icons you can decide where a glue point will be placed when the size of the object is changed.