If you call this function from the menu a dialog box will
appear showing the current signal. Changing one of the parameters
will result in an automatic change of the corresponding
parameter after you have pressed the TAB or RETURN key.
The new size and the
selected interval of the signal are also displayed.
Warning: This will not happen if you forget to press TAB/RETURN/ENTER, e.g. if you choose the next input box via mouse.
y = CutByIndex(x,a,b);
y = CutByValue(x,a,b);