ui: transaction: show all decimal places (like print, cf #931)

On the accounts screen and register screen we round amounts according
to commodity styles, but when you drill down to a transaction you
probably want to see the unrounded amounts.

hledger-lib/Hledger/Data/Transaction.hs

@@ -37,6 +37,7 @@ module Hledger.Data.Transaction (
   transactionToCost,
   transactionApplyAliases,
   transactionMapPostings,
+  transactionMapPostingAmounts,
   -- nonzerobalanceerror,
   -- * date operations
   transactionDate2,
@@ -623,6 +624,9 @@ transactionMapPostings :: (Posting -> Posting) -> Transaction -> Transaction
 transactionMapPostings f t@Transaction{tpostings=ps} = t{tpostings=map f ps}
 
 -- | Apply a transformation to a transaction's posting amounts.
+transactionMapPostingAmounts :: (Amount -> Amount) -> Transaction -> Transaction
+transactionMapPostingAmounts f  = transactionMapPostings (postingTransformAmount (mapMixedAmount f))
+
 -- tests
 
 tests_Transaction :: TestTree

hledger-ui/Hledger/UI/TransactionScreen.hs

@@ -60,7 +60,7 @@ tsInit _ _ _ = error "init function called with wrong screen type, should not ha
 tsDraw :: UIState -> [Widget Name]
 tsDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportspec_=rspec@ReportSpec{rsOpts=ropts}}}
               ,ajournal=j
-              ,aScreen=TransactionScreen{tsTransaction=(i,t)
+              ,aScreen=TransactionScreen{tsTransaction=(i,t')
                                         ,tsTransactions=nts
                                         ,tsAccount=acct
                                         }
@@ -71,6 +71,8 @@ tsDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportspec_=rspec@ReportSpec{
     -- Minibuffer e -> [minibuffer e, maincontent]
     _          -> [maincontent]
   where
+    -- as with print, show amounts with all of their decimal places
+    t = transactionMapPostingAmounts setFullPrecision t'
     maincontent = Widget Greedy Greedy $ do
       let
         prices = journalPriceOracle (infer_value_ ropts) j