How can I display a Clock ( current time field ) on a FILEMAKER Pro screen layout

You could create a calculation field that does  Get ( CurrentTimeStamp ).  Make the sure that you set the storage options to either "Do not store calculation results" or "Use global storage" if you want the field to always calculate.

Note:  if you don't set it as global it will have to calculate for every record when you first launch the application.  This can be a performance issue if you have a large number of records.

Thats fine when you open the file, get the current time at that instance, but I need a field to continuous display the current time - just like a clock

Anytime you make a change to a record it will recalculate.  What I have not been able to do in a simple way (there may be scripting/event triggers/etc... that could be used) is to open a layout and see the seconds tick by.

What level of change would you want this to be? Minutes or Seconds?

Thats exactly what I want - to open a layout and see the seconds tick by, just like at clock.
Is there anyway to link at field to a website which provides GMT - like "NetTime"?

Seconds

You got me thinking about how to use the web.

Edit your layout and select Insert->Web Viewer...  Select Custom Web Address and put in the web address of your choice.  (I used http://www.time.gov/timezone.cgi?Mountain/d/-7/java)  Bingo.  You now have a clock displayed...

I forgot to mention.  You can even interact with the web viewer.  So, for example the  site I used has a button that can select a different time zone.  I can click the button and change the zone all from FileMaker.  Very cool...

Wow Its nearly there - I'm getting webpage cannot be displayed - Do you put "" marks around the http address in Custom Web Address setup box

A Great Solution!! I used a GMT website and it worked - I will be using this solution in other projects - WOW THANK YOU