The present disclosure provides a method for providing composite user interface controls and a library or online storefront for same. In one aspect, there is provided a method for a client computer of sharing a custom control, comprising: receiving by a browser an encrypted custom control comprising a number of user interface elements which are positioned in a specified manner with respect to each other, wherein each of the user interface elements has one or more properties; receiving by the browser a decryption key; and decrypting by the browser the encrypted custom control using the decryption key.