[Zope-CMF] Problem with the portlet calendar

[Mike Jaeger]

Hello members of the zope-cmf-list,

I have a question regarding the portlet calendar in Plone.
After entering an event, which takes for example 2 weeks (project), the timeframe is marked on blue background. I would like to have that only the start and finish date are marked, the dates between start and finish date should remain on white background. I have looked in the code of CalendarTool.py and calendar_portlet, but it wasn't crowned with success. I have also looked for the problem in the internet, but I thing that I am the first person who requires this feature. Any idea how to get this feature without big hacking?
Is it possible to modify the queries on the portal_catalog?
Thank you in advance. 

Regards
    Mike