hi,
Cursors.
Plot the trace as usual.
Right click on the plot name above the plot.
A small window will appear, where it says 'Attach cursor' , click the drop down box and select '1st and 2nd', then OK.
You sgould now see two new dash lines on the plot, move your cursor over the dashed line and a number 1 or 2 will appear.
Drag the '1' to a point on the plot you want to measure, then drag the '2' to the second point on the plot that you want to measure too.
There should be a window in right bottom of the screen that shows the values represented by the cursors 1 and 2 positions.
EDIT: saw your new post after I started typing.! anyway here it is...