Hello,

whenever I do a right-click on a category or payee and select "open operations", I get a page with "sub operations". I don't understand what these operations are?
They seem to have different comments, e.g. I edited a comment in the operations tab from "aaa" to "bbb".
The new comment is shown in the operations view as "comment: bbb", but when called by "open operation" from the payee view, it reads "sub comment: aaa".

Why is the old comment shown in there and why is it called a "sub comment" or "sub operation"

In fact, in Skrooge, an operation is a container of one or more suboperations.
This is used for split operations.
Here is an example:
operation: date=16/12/2012, Payee=My Supermarket, comment=bbb ==> amount is computed by adding suboperations = 30€
|--- suboperation: amount=10 €, category=book, comment=aaa
|--- suboperation: amount=20 €, category=food, comment=miam miam

Event if the operation is not split, this is like this
operation: date=16/12/2012, Payee=My Supermarket, comment=bbb ==> amount is computed by adding suboperations = 10€
|--- suboperation: amount=10 €, category=book, comment=aaa

As you can see, you can set a comment on the operation or on suboperations.
In you case, aaa is the comment of the operation, bbb is the comment of the suboperation.
I will do a change to align comments of operation and suboperation for operation having only one suboperation.

Ok I seem to understand the concept, but still it seems to behave wrong in my opinion. I have an operation with a comment "Alien Legacy DVD" and the category "Entertainment > DVD". If I open the operations for this category from the category view, I get the suboperation with the comment "2944661327442528" (some old comment added from my online banking software).
If I open the operation for this suboperation, I get the correct comment again. If I switch to the "Split" view of that operation, it still displays the correct comment. I'll try to add screenshots to show my problem...

Opening the suboperations from the category view:




Double clicking the suboperation will give me the corresponding operation with the correct comment:

This is normal.
As said, the categorie is associated to the suboperation, not to the operation itself.
So, by double clicking on the category, you have the list of suboperations.
In the operation page, you can see categories, in fact this is the most important category of the operation.
For examples:
operation: date=16/12/2012, Payee=My Supermarket, comment=bbb ==> amount is computed by adding suboperations = 30€
|--- suboperation: amount=10 €, category=book, comment=aaa
|--- suboperation: amount=20 €, category=food, comment=miam miam

This operation will be display with category=food because 20€>10€

If the operation is not split of course you will have the category of the only on suboperation.

Be aware, that I added a new advice detecting not aligned comment for single operation and a cleaning function to align the comment of the suboperation with the comment of the operation.
I think this function could be a solution to your issue.