PositionPicker.css

.parent {
  width: 150px;
}
.position {
  width: 49px;
  height: 50px;
  border: 1px solid #aaa;
  display: inline-block;
  padding: 0;
  margin-right: -1px;
  margin-bottom: -1px;
}

.position:hover,  .selected {
    background-color: #ea42b2;
    cursor: pointer;
}

.label {
  margin: 20px;
}

PositionPicker.js

var Position = React.createClass({
  render: function() {  
  	let classes = "position " + (this.props.selected ? 'selected' : '');
    return <div className={classes}
              onClick={() => {this.props.handler(this)}}>{this.props.position}
          </div>;
  }
});

var PositionPicker = React.createClass({
	getInitialState: function() {
    return {pos: '', rects: []};
  },
  
  createChilds: function() {
    let childs = this.props.positions;
    
    let itemHandler = (item) => {    	
      this.setState({pos: item.props.position});      
      this.props.onChange(item.props.position);
    }
    
    let rects = childs.map((item) => {         
      let selected = this.state.pos ? item === this.state.pos : this.props.defaultPosition === item;
     	return (
      	<Position position={item} 
        					key={item} 
                  selected={selected}
                  handler={itemHandler}/>
      )
    })
    this.state.rects = rects;
    
		return <div className="parent">{this.state.rects}</div>  	
  },
  render: function() {    
    return <div>{this.createChilds()}</div>
  }
});

var App = React.createClass({
	getInitialState: function() {
    return {selection: 'BR'};
  },
  
  userSelection: function(selection){  	
    this.setState({selection});
  },
  
  render: function() {
    return ( 
    <div>
    		<div className="label">Hello {this.props.name}</div>
        
        <PositionPicker onChange={this.userSelection} 
        		positions={['TL',2,3,4,5,6,7,8,'BR']} 
            defaultPosition="TL"/>
            
       <div className="label">User selection: {this.state.selection}</div>     
    </div>
  )}
});

ReactDOM.render(
	<div>
  	<App name="Position Picker" /><br/>    
  </div>,  
  document.getElementById('container')
);

https://jsfiddle.net/tm84q9pn/12/