about your comments...

Description

Actually I don't see that Streber will ever "create" any invoice. I just want to store and manage invoice information. We cannot and should not try to do a job, Excel can do better. I want the handle meta-information and probably attach a PDF document created with a decent text program.

The workflow would be like this:
  1. Book Efforts (Time and Expenses) for a project.
  2. In projViewEfforts select 'billable' Efforts and use Create New Invoice function to link those Efforts with an invoice. An Effort could be linked to One Invoice only.
  3. The new invoice is displayed listing the efforts and summing them up. I could export these efforts as CSV-list and finetune the list with StarOffice, create an PDF.
  4. I would attach the PDF to the invoice for reference only.
  5. I would fill out dates for sent and due and the invoice number.
  6. When the client as paid the invoice I set its status to Paid.
  7. When I sent the invoice to my tax consultant I set the status to booked.

I also do not see any relation ship between Invoice and Task. Only between Invoice and Effort.

I don't want to clutter the interface with information which is irrelevant for most users. So I see only two links for invoices:
  • In home a link to all invoices probably highlighting the open ones.
  • In project View a link in the Details block
Although most of you features would be nice, they might be overdone for Streber. How was the principle? Keep it Simple and Stupid. Most of those features could be done with duplicating Efforts. But I confirm on adding Efforts of another project to an Invoice would be nice.