Add warning of higher failure risk since app proposed gasLimit.

ui/app/components/pending-tx.js

@@ -52,7 +52,8 @@ PendingTx.prototype.render = function () {
   const gas = txParams.gas
   const gasBn = hexToBn(gas)
   const gasLimit = new BN(parseInt(blockGasLimit))
-  const safeGasLimit = this.bnMultiplyByFraction(gasLimit, 19, 20).toString(10)
+  const safeGasLimitBN = this.bnMultiplyByFraction(gasLimit, 19, 20)
+  const safeGasLimit = safeGasLimitBN.toString(10)
 
   // Gas Price
   const gasPrice = txParams.gasPrice || MIN_GAS_PRICE_BN.toString(16)
@@ -66,6 +67,8 @@ PendingTx.prototype.render = function () {
 
   const balanceBn = hexToBn(balance)
   const insufficientBalance = balanceBn.lt(maxCost)
+  const dangerousGasLimit = gasBn.gte(safeGasLimitBN)
+  const gasLimitSpecified = txMeta.gasLimitSpecified
   const buyDisabled = insufficientBalance || !this.state.valid || !isValidAddress || this.state.submitting
   const showRejectAll = props.unconfTxListLength > 1
 
@@ -263,11 +266,14 @@ PendingTx.prototype.render = function () {
             text-transform: uppercase;
           }
         `),
-
+        h('.cell.row', {
+          style: {
+            textAlign: 'center',
+          },
+        }, [
           txMeta.simulationFails ?
             h('.error', {
               style: {
-              marginLeft: 50,
                 fontSize: '0.9em',
               },
             }, 'Transaction Error. Exception thrown in contract code.')
@@ -276,7 +282,6 @@ PendingTx.prototype.render = function () {
           !isValidAddress ?
             h('.error', {
               style: {
-              marginLeft: 50,
                 fontSize: '0.9em',
               },
             }, 'Recipient address is invalid. Sending this transaction will result in a loss of ETH.')
@@ -285,12 +290,21 @@ PendingTx.prototype.render = function () {
           insufficientBalance ?
             h('span.error', {
               style: {
-              marginLeft: 50,
                 fontSize: '0.9em',
               },
             }, 'Insufficient balance for transaction')
           : null,
 
+          (dangerousGasLimit && gasLimitSpecified) ?
+            h('span.error', {
+              style: {
+                fontSize: '0.9em',
+              },
+            }, 'Gas limit set dangerously high. Approving this transaction is likely to fail.')
+          : null,
+        ]),
+
+
         // send + cancel
         h('.flex-row.flex-space-around.conf-buttons', {
           style: {