There are two common requirement:
1) Drag a selected block of code from one position to
2) Copy a line or block of lines to use it as the basis
of a new block.
It is less likely that the user will want the combined
operation as provided by DrPython. It is inconvenient
to have to delete the unwanted original code which is
nolonger highlighted after the copy.
In the event that the user does want a copy it could be
achieved in two operations. Click to duplicate then
drag to move it.