When the dividents of foreign security (e.g. Security_X_Eur) are payed out, they are paid in original currency (e.g. USD). To be able to properly book it, I set up a new security in the orignal currency (e.g. Security_X_Usd) and then book the dividend on this security. However this dividend would then not be shown and calculated in Performance Calculation, as it is missing the buying transaction.
Perhaps this could be fixed in the way that if the security is already bought in different currency (e.g. as Security_X_Eur) then identify it through ISIN (ISIN for both Securities is the same) and check if there was a buying transaction. If so then account for the dividend (payed in USD through Security_X_Usd) in the Performance Calculation.