I use several buttons to jump to predefined dates in calendar. This can be done using dpc1.commandCallBack('command', date);. Unfortunately, the Navigator does not reflect the changes in calendar. How can I set startDate and selectionStart in Navigator (on client side or from the commandCallBack in code behind)?

I tried the following (javascript):

dpn1.startDate = new Date();
dpn1.selectionStart = new Date();
dpn1.updateSelection();

This doesn't work. May be I'm completely wrong.
Also i could not find any documentation on the navigator client side api.

Any hints on this?