function inner_before_change(e)
	{
		if(this.callback_before) this.callback_before(e);
	}
Widget to edit two numbers (it adds a dragging mini widget in the right side)
@method addVector2
@param {string} name 
@param {vec2} value 
@param {Object} options, here is a list for this widget (check createWidget for a list of generic options):
- callback: function to call once the value changes
- disabled: shows the widget disabled
- callback: function to call when the string is edited
- precision: number of digits after the colon
- units: string to show after the number
- min: minimum value accepted
- max: maximum value accepted
- step: increments when draggin the mouse (default is 0.1)
@return {HTMLElement} the widget in the form of the DOM element that contains it