We are in the process of migrating developers from SQL Navigator to PL/SQL Developer ( The most awesome tool ). One of the biggest complains that we receive is that in PLSQLD we can
People usually do this awkward mouse-dragging thing because SQLN's code completion is so painfully slow that it becomes almost useless. It is faster to run a "select *", break (though breaking is also a pain there) and drag columns than to wait for completion window.
So, no, after you really start using PLSD, you won't miss this feature that much.