Fees and expenses in a case are billed in the same way, by generating an invoice.  When client sends a check, they do not specify if the check is for fees or expenses.  So you pay the invoices agnostic to whether the payment is for fees or for expenses.  Incorporating billing and payment for fees and expenses separately will make the interface confusing and difficult to use.

On the Dashboard, if you click on the Invoices and Payments button, an Excel file will be downloaded.  The Excel file will include listing of invoices including how much was fees and how much was expenses for each invoice, and also remaining due.  If all invoices are paid in full, the total of "Expenses" column will be the payments against expenses.  If invoices are not paid in full, the expenses may be treated as paid in full and the deficiencies may be attributed to fees.

From our understanding, what is billed to the client for expenses may not be the correct figures for tax purposes because say if the client is billed for copies, that part may not be tax deductible as expense.  In stead, the cost of paper and ink is what may be deductible.  These out of the pocket expenses should be entered in the Ledger or may be tracked separately from credit card or bank accounts that are specifically used for paying expenses.