Gallery control with dynamically determined control template replica sizes

Techniques are described for rendering a gallery control to a graphical user interface (GUI), the gallery control including first and second template replicas. For each template replica, a GUI-rendering component is instructed to render the template replica, a read application programming interface (API) call is placed to the GUI-rendering component, a target size of the template replica is determined based on the results of the read API call, and a write API call is scheduled to instruct the GUI-rendering component to update the dimension of the template replica to the target size. In response to determining that the target size of the dimension of either template replica is different than a default size, a write API call is placed to the GUI-rendering component to update an offset associated with each template replica and the scheduled write API calls are placed to the GUI-rendering component.