function inner() {
			var value = input.value;
			if(this.dataset && this.dataset["value"] == "cancel")
				value = null;
			dialog.close(); //close before callback
			if(callback)
				callback( value );
		}
Shows a prompt dialog with a message
@method prompt
@param {String} content
@param {Function} callback
@param {Object} options ( title, width, height, content, noclose )