getVisibleSelectionRect testing

TextEditor.js

      <div styleName="container">
          <Toolbar
            editorState={editorState}
            onChange={this.onEditorChange}
            boundingRect={boundingRect} />
          <Editor
            editorState={editorState}
            onChange={this.onEditorChange}
            customStyleMap={styleMap}
            placeholder="Enter your text.." />
      </div>
The condition ive used to hide and show the toolbar is this:

Toolbar.js

const boundingRect = getVisibleSelectionRect(window); (passed from parent component)
const selectionState = editorState.getSelection();

if (boundingRect && !selectionState.isCollapsed() && selectionState.getHasFocus()) {
      var toolbar =
        <div
          styleName="container"
          style={{top: boundingRect.top, left: boundingRect.left + boundingRect.width/2}}>
            ...buttons
        </div>
}

//which is returned in render
    return (
      <span>
        {toolbar}
      </span>
    )
.container {
  position: fixed;
  transform: translate3d(-50%, calc(-100% - 5px), 0);
  max-width: 300px;
  z-index: 80;
}