Landscape selection

When I am dragging meshes around the world using the blue red and green arrows it sometimes select my landscape when I let go of the button. Actually it seems to be selecting what the cursor is pointing at it is just often the landscape. It’s like I am double clicking which I am not. I am not sure if it also moves the landscape a little bit but if I press undo it takes a long time for it to do it and often auto saves right after. Anyone knows what is going on?