I can't figure out the offset command. I am trying to move the selected rectangle to a set distance from the nearby lines but I can't figure out how to do it. Offset seems to produce more lines from the selected ones. Is there a way to move to a relative position like this?
I don't know of an explicit "offset" command but you do mention moving the object so I'm going to assume that is what you mean. I am also assuming you want to keep the rectangle parallel to the two lines that make up the corner. I would use a polar coordinate. For this to work you have to know two things. One is the distance you want to move the object, and the second is the angle. Then select the object you want to move. LibreCad will ask you to specify a reference point. Click on any point on the object, then specify a target point. This is where you would enter the polar coordinate. Do this by typing a<b where a is the distance you want to move the object and b is the angle. Angles start at 0 on a horizontal plane and increase counterclockwise. Think of a clock face. 0 degrees would be at three o'clock, 90 at twelve, 180 at 9 and 270 at 6 o'clock. You can use negative numbers to move clockwise. -90 degrees = 270 degrees. For example, you want to move the object 12 units up and to the right at an angle of 45 degrees you would type 12<45. (Or 12<-315.) After selecting the object, specifying a reference point and a target point a screen will pop up with the Move/Copy options. You can Delete the original, Keep the original or Multiple Copies. The first two are self evident. The third will create the number of copies you specify. If you enter 3 you will end up with 4 rectangles.
Another way would be to use absolute coordinates if you know the exact x,y location you want to move the object to. Use the Move/Copy command, select the reference point (the corner with the red circle in your screen shot) and then use the keyboard to enter the x,y values, i.e. 25,78.
There are other ways to accomplish this so keep asking if you still have trouble.
Thanks Philip for the detailed and helpful reply! I ended up making the move by drawing another box in the corner of the perimeter and using the top corner of that box as a set point to move to and then deleting the box.