Imbalance fraction testing: Check all of the account SCUs too.

An account might have a fixed SCU denominator that's less
than the commodity's denominator and that can also create an
unbalanceable transaction.

gnucash/register/ledger-core/split-register-control.cpp

@@ -49,6 +49,34 @@
 /* This static indicates the debugging module that this .o belongs to. */
 static QofLogModule log_module = GNC_MOD_LEDGER;
 
+static inline bool
+check_imbalance_fraction (const SplitRegister* reg,
+ const gnc_monetary* imbal_mon,
+ const Transaction* trans)
+{
+ auto commodity_fraction{gnc_commodity_get_fraction (imbal_mon->commodity)};
+ auto denom_diff = imbal_mon->value.denom > commodity_fraction;
+ if (!denom_diff)
+ {
+ const auto imbal_comm = imbal_mon->commodity;
+ for (auto node = xaccTransGetSplitList(trans); node;
+ node = g_list_next(node))
+ {
+ auto acc = xaccSplitGetAccount(GNC_SPLIT (node->data));
+ if (xaccAccountGetCommodity(acc) == imbal_comm &&
+ imbal_mon->value.denom > xaccAccountGetCommoditySCU (acc))
+ {
+ denom_diff = true;
+ break;
+ }
+ }
+ }
+
+ if (denom_diff)
+ gnc_error_dialog(gnc_ui_get_main_window(GTK_WIDGET(reg)), "%s", _("This transaction cannot be balanced: The imbalance is a fraction smaller than the commodity allows."));
+
+ return denom_diff;
+}
 
 static gboolean
 gnc_split_register_balance_trans (SplitRegister *reg, Transaction *trans)
@@ -91,12 +119,9 @@ gnc_split_register_balance_trans (SplitRegister *reg, Transaction *trans)
  multi_currency = FALSE;
  else
  multi_currency = TRUE;
- if (multi_currency &&
- imbal_mon->value.denom > gnc_commodity_get_fraction(imbal_mon->commodity))
- {
- gnc_error_dialog(gnc_ui_get_main_window(GTK_WIDGET(reg)), "%s", _("This transaction cannot be balanced: The imbalance is a fraction smaller than the commodity allows."));
+
+ if (multi_currency && check_imbalance_fraction (reg, imbal_mon, trans))
  return FALSE;
- }
  }
 
  /* We're done with the imbalance list, the real work will be done