Numeric input of in- and out-points

It’s really hard to shorten a videoclip by i.e. exact 2 seconds with the mouse! Especially when the videoclip is very long.
I would like to just click on the timecode and enter my out-point.

I found a workaround by editing the property-list-file of the show. But I would definitely recommend to add this feature.

I also found in the help manual that this should work with the tune button, but I cannot activate it.
Can anybody help me how I get to this controls?

So now I found out it only works if pan & zoom is enabled… why?