New Twiddle

a-handle.component.js

import Ember from 'ember';

export default Ember.Component.extend({
	attributeBindings: ["draggable"],
  classNames: ["a-handle"],
  draggable: true,
  
  dragStart(e) {
    this.set("origX", e.originalEvent.clientX);
    this.set("origWidth", parseInt(this.$().closest("th,td").css("width").replace(/px$/, ""), 10));
  },
  
  drag(e) {
    const newX = e.originalEvent.clientX;

    if (newX > 0) {
      this.sendAction("resize",
          this.get("origWidth") - this.get("origX") + newX);
    }
  },
  
  dragEnd(e) {
    this.set("origX", false);
  }
});

a-handle.template.hbs

  

application.controller.js

import Ember from 'ember';

const {
  computed
} = Ember;

export default Ember.Controller.extend({
  actions: {
    resize(column, width) {
      if (width > 10) {
        const fullWidth = this.get("fullWidth");

        if (column === "a") {
          let newBWidth = fullWidth - this.get("cWidthPx") - width;
          if (newBWidth > 10) {
            this.set("aWidthPx", width);
            this.set("bWidthPx", newBWidth);
          }
        } else {
          let newCWidth = fullWidth - this.get("aWidthPx") - width;
          if (newCWidth > 10) {
            this.set("bWidthPx", width);
            this.set("cWidthPx", newCWidth);
          }
        }
      }
    }
  },
  
  aWidthPx: 150,
  
  aWidth: computed("aWidthPx", function() {
    return `width: ${this.get("aWidthPx")}px`;
  }),
  
  bWidthPx: 150,
  
  bWidth: computed("bWidthPx", function() {
    return `width: ${this.get("bWidthPx")}px`;
  }),
  
  cWidthPx: 150,
  
  cWidth: computed("cWidthPx", function() {
    return `width: ${this.get("cWidthPx")}px`;
  }),
  
  fullWidth: 450,
  
 	fullWidthStyle: computed("fullWidth", function() {
    return `width: ${this.get("fullWidth")}px`;
  }),
  
  appName: 'Ember Twiddle'
  
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<table style={{fullWidthStyle}}>
  <tr>
    <th style={{aWidth}}>a{{a-handle resize=(action "resize" "a")}}</th>
    <th style={{bWidth}}>b{{a-handle resize=(action "resize" "b")}}</th>
    <th style={{cWidth}}>c</th>
  </tr>
  <tr>
  	<td><div class="ellipsis" style={{aWidth}}>Lorem Ipsum Lorem Ipsum Lorem Ipsum</div></td>
    <td>B</td>
    <td>C</td>
  </tr>
</table>
{{outlet}}
<br>
<br>

styles.app.css

* {
  box-sizing: border-box;
}

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.a-handle {
  display:block;
  width:1px;
  height: 100%;
  background: transparent;
  float: right;
  cursor: ew-resize
}

table {
  border-collapse: collapse;
}

table, td, th, tr {
  padding: 0;
  margin: 0;
}

td, th {
  border: 1px solid black
}

.ellipsis{
  width: auto;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

twiddle.json

{
  "version": "0.6.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}