The Dashboard-Widget 'Incomes & Expenses' shows incorrect values with split operations.

For example do an operation which costs -100,- in total.
If you split it into two operations, the widget shows -200,-, if you split it into ten operations, the widget shows -1000,-.

Reproducible: Always

Steps to Reproduce:
1. Create a new file with a new account and initial balance 0,-
2. Go to operations and do a split operation with total amount of -100,-, e.g. spend -25,- to four categories
Actual Results:  
Go to accounts: the account now has -100,-; that's correct
But now go to the dashboard: the widget shows expenses of -400,-; that's not correct

Expected Results:  
The widgedt is expected to show -100,-

There's no difference whether the operations correspond to income or to expenses.