Kicking myself for not finding these sooner so, posting in line with the current trend of highlighting little Flex time-savers. Two ActionScript editor short-cuts (and probably apply to any Eclipse code editor?)…
1. Select some code in the ActionScript editor and press Option-Up or Option-Down, and the selected block of code gets moved accordingly. Or just place the cursor on a line if you only wish to move a single line. Saves a load of messing with Cut-Paste.
2. Need to duplicate a line? Place the cursor at the start of the line and press either CMD-Option-Up or CMD-Option-Down, and the current line (or selection if you have one) gets duped above or below the cursor respectively.
With either of the above, if you make a selection, you don’t need to be character accurate. The movement is applied either to the line touched by the cursor, or the lines touched by the selection. i.e. If you select part of a line, the whole of that line is included in the selection to be moved.