From Stewart Butterfield's quick links blog:

QUOTE:

Human beings cannot pay attention to their task and to system state at the same time. Mode errors are caused by the system responding differently to a particular user gesture when the system is in different internal states. Interface designers have known about and published papers about the difficulties caused by modes since at least the early 1970s. Nonetheless, they continue to design modes into interfaces and thus continue to ill-serve users. There is much more to be said about modes and why you can't solve the problem with mode indicators, but there is not room here to discuss the subject (I wrote about it in detail in my book, The Humane Interface, Addison-Wesley, 2000).

A very few systems avoid the entire issue by using a "move" command. You make a selection, which persists (and so remains visible and in its place) while you move the cursor to the target location. You then issue the move command (which requires no more effort than that required to issue the paste command) and the selection moves. Not only have we eliminated one command (before you had to issue both cut and paste commands; now you issue one move command), but the text you are moving never vanishes; and if you start a second move before completing the first, nothing is lost.

That such a simple solution exists, has been available for decades, yet is rarely used shows how interface designers have become slaves of fashion and how corralled they are by convention.