disable Send button when tip amount <= 0 or tip amount > balance

src/renderer/component/walletSendTip/index.js

@@ -4,6 +4,7 @@ import {
   makeSelectTitleForUri,
   makeSelectClaimForUri,
   selectIsSendingSupport,
+  selectBalance,
 } from 'lbry-redux';
 import WalletSendTip from './view';
 
@@ -11,6 +12,7 @@ const select = (state, props) => ({
   isPending: selectIsSendingSupport(state),
   title: makeSelectTitleForUri(props.uri)(state),
   claim: makeSelectClaimForUri(props.uri)(state),
+  balance: selectBalance(state),
 });
 
 const perform = dispatch => ({

src/renderer/component/walletSendTip/view.jsx

@@ -14,6 +14,7 @@ type Props = {
   sendSupport: (number, string, string) => void,
   onCancel: () => void,
   sendTipCallback?: () => void,
+  balance: number,
 };
 
 type State = {
@@ -51,7 +52,8 @@ class WalletSendTip extends React.PureComponent<Props, State> {
   }
 
   render() {
-    const { title, errorMessage, isPending, uri, onCancel } = this.props;
+    const { title, errorMessage, isPending, uri, onCancel, balance } = this.props;
+    const { amount } = this.state;
 
     return (
       <div>
@@ -82,7 +84,7 @@ class WalletSendTip extends React.PureComponent<Props, State> {
             <Button
               button="primary"
               label={__('Send')}
-              disabled={isPending}
+              disabled={isPending || amount <= 0 || amount > balance}
               onClick={this.handleSendButtonClicked}
             />
             <Button button="alt" label={__('Cancel')} onClick={onCancel} navigateParams={{ uri }} />