If you want to edit a lot of notes, I recommend you use Process | Find/Change. This is much faster and works in Staff View as well as anywhere else.
This example, for simplicity, assumes you have a resolution of 120 ticks per quarter, but it will work with any resolution as long as you know how many ticks are in the longest and shortest note. it also assumes you have quantized durations.
• In this example, pretend you are editing half notes (240 ticks), quarter notes (120 ticks), eighth notes (60 ticks), and sixteenth notes (30 ticks). Assume you want to shorten the notes by 2 ticks.
• Select the range you want to change.
• Go to Process | Find/Change. Click ALL on the first screen. Then enter 30 and 240 in the two duration boxes. (You will need to precede the numbers with 0 and space, like 0 30, to make sure you get ticks and not beats).
• On the second screen Click ALL and then enter 28 and 238 in the duration boxes to shorten all the values by 2 ticks.
Find/Change used to be called Interpolate which is a more accurate description of how this works since it edits intermediate values proportionally. You will be amazed what you can do with this function: change crescendos/decresendos, scale pitch wheel movements, edit velocities, and many other things.