Localize some things

src/containers/backdrop-library.jsx

 import bindAll from 'lodash.bindall';
 import PropTypes from 'prop-types';
 import React from 'react';
+import {injectIntl, FormattedMessage} from 'react-intl';
 import VM from 'scratch-vm';
 
 import analytics from '../lib/analytics';
@@ -36,7 +37,13 @@ class BackdropLibrary extends React.Component {
             <LibraryComponent
                 data={backdropLibraryContent}
                 tags={backdropTags}
-                title="Choose a Backdrop"
+                title={
+                    <FormattedMessage
+                        defaultMessage="Choose a Backdrop"
+                        description="Heading for the backdrop library"
+                        id="gui.backdropLibrary.chooseABackdrop"
+                    />
+                }
                 onItemSelected={this.handleItemSelect}
                 onRequestClose={this.props.onRequestClose}
             />
@@ -49,4 +56,4 @@ BackdropLibrary.propTypes = {
     vm: PropTypes.instanceOf(VM).isRequired
 };
 
-export default BackdropLibrary;
+export default injectIntl(BackdropLibrary);

src/containers/sound-library.jsx

 import bindAll from 'lodash.bindall';
 import PropTypes from 'prop-types';
 import React from 'react';
+import {injectIntl, FormattedMessage} from 'react-intl';
 import VM from 'scratch-vm';
 import AudioEngine from 'scratch-audio';
 
@@ -85,7 +86,13 @@ class SoundLibrary extends React.PureComponent {
             <LibraryComponent
                 data={soundLibraryThumbnailData}
                 tags={soundTags}
-                title="Choose a Sound"
+                title={
+                    <FormattedMessage
+                        defaultMessage="Choose a Sound"
+                        description="Heading for the sound library"
+                        id="gui.soundLibrary.chooseASound"
+                    />
+                }
                 onItemMouseEnter={this.handleItemMouseEnter}
                 onItemMouseLeave={this.handleItemMouseLeave}
                 onItemSelected={this.handleItemSelected}
@@ -101,4 +108,4 @@ SoundLibrary.propTypes = {
     vm: PropTypes.instanceOf(VM).isRequired
 };
 
-export default SoundLibrary;
+export default injectIntl(SoundLibrary);

src/containers/sprite-library.jsx

@@ -76,9 +76,9 @@ class SpriteLibrary extends React.PureComponent {
                 tags={spriteTags}
                 title={
                     <FormattedMessage
-                        defaultMessage="Sprite Library"
+                        defaultMessage="Choose a Sprite"
                         description="Heading for the sprite library"
-                        id="gui.spriteLibrary.spriteLibrary"
+                        id="gui.spriteLibrary.chooseASprite"
                     />
                 }
                 onItemMouseEnter={this.handleMouseEnter}