Unlike SISO block in Simulink, blocks that have a single inport and no outport (Scope, Display, To File, To Workspace) do not autoconnect if dragged over a line in a model. Placing a call to this function in the CopyFcn callback of any single-inport block will cause the block to automatically connect when the block is dropped over a line in a Simulink model. This is similar to the built-in behavior of SISO blocks (ie gain, unit delay, etc) in Simulink. These blocks, when dropped on a line, automatically connects the inport and outport. With this function, in this case of a single-inport block, the block is moved just below the line and the inport is automatically connected.
This can be made the default behavior for these blocks by creating a custom library containing the desired blocks and adding the call to this function in the CopyFcn callback of the library blocks.