Budgets and expenses list can be accessed even when not on screen

[nus-pe-bot]

As is described. Running the edit command for both budgets and expenses will work even if not displayed

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_{[original: nus-cs2103-AY1920S1/pe-interim#221]}

[choonx99]

Team's Response

Running EditExpense command will only work when the user is viewing an expense list in the centre panel this is because there are multiple expense lists, default expense list and the individual expense lists inside budgets, the app needs to know which expense list the expense is in for the user to edit.
However we allowed EditBudget to work at anytime when the EditBudget command is called as long as the user knows which budget (by index) he/she wants to edit is because there is only 1 budget list in the app. This is the same for viewing a specific budget, users need not be viewing the budget list in order to view or edit a specific budget as long as he/she can remember the index. We made this possible to increase usability as users may not want to always be required to call listBudgets command first before they are allowed to view or edit a budget even though they may know exactly which budget they want to interact with.

Duplicate status (if any):

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