Editing in 3.0 is different Can't operate mouse and keyboard at same time

[UPDATE.....I'll try to make this clearer:]

Perhaps I've overlooked a "box" that I should have checked, but editing is different in my 3.0. In 2.0....I could highlight a section...and listen, and then if I wanted to stretch or shorten the highlighted section....I would simply drag (extend the highlighted section) to the right or left a bit...and if the highlighted area was still playing....I could hit the space bar and it would immediately start playing from my new location......WITHOUT having to manually STOP playing and hit START again...before it would play my new edit point.

Hope I've explained that clearly enough.  Surely there's a way to get 3.0 to edit as conveniently as 2.0.

What am I doing wrong?

GP

UPDATE.....I'll try to make this clearer:    When I HIGHLIGHT a segement for editing, in 2.0.....I could keep holding the mouse down and hit the space key on the keyboard.....and it would start and stop....

With 3.0......I can no longer hold the mouse (left) button down....then hit the space key...and have the file start playing again..........at the new highlighted location...without releasing the mouse button.

I COULD do this on 2.0.

Any ideas why?

Thanks,

-lee