How to connect two entity by a line like that way?

Dear every expert.

I want to implement such function like that.

take two rectangle for example.

I want to connect two rectange by a line.
firstly click mouse to decide start point. the expected behavior is that it will snap to the edge of first rectangle automatically.
then I will drag the line until mouse point snap to the edge of the second rectangle automatically.

I dont' want to snap to the edge of the two entity mannually . and it always turn out to be inaccuracy.

I am not sure whether it's already supported by LibreCAD. Could someone point out the way to do that ?

Thanks.

Johnson