Points may not be moved arbitrarily, if
  • they are bound to a line or a circle,
  • intersections of objects,
  • fixed by the user.

You will also learn about the move tool.

 

Generate a segment, and another segment with one endpoint on the first segment. like in the top figure.

Of course, the endpoint cannot be moved from the segment. However, you can release the point. Open its properties dialog with a right click on the point, and exit with the button to release the binding.

Now generate two crossing segments, and a third one with one endpoint in the intersection.

As you move the endpoints of the first segments, the intersection, and thus the third segment will follow. The segment will disappear (become invalid), if the segments no longer intersect!

Note that you cannot move segments in this program by dragging them. However you can move both endpoints simultaneously with move tool. To do this, select the move tool, shift click the first endpoint, and drag  the second with the left mouse button.

Note that the move tool flashes all moveable objects, when it is loaded. E.g., the intersection does not flash. As you can read in the description of the move tool, you can ctrl-move objects and the old state will remain visible.

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