function inner_before_change(e)
	{
		if(this.callback_before) 
			this.callback_before.call(element);
	}
Widget to edit numbers (it adds a dragging mini widget in the right side)
@method addNumber
@param {string} name 
@param {number} value 
@param {Object} options, here is a list for this widget (check createWidget for a list of generic options):
- 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