1. A head-mountable display (HMD) system comprising: a non-transitory computer-readable medium; and program instructions stored on the non-transitory computer-readable medium and executable by a processor to: provide a multimode input field in a graphical display of a head-mountable display (HMD), wherein the multimode input field is a single graphical interface element that is controllable to display content based on a plurality of modalities of input data received from any of a plurality of input sources, and wherein the plurality of modalities comprises point-of-view video and at least one of audio, image, text, and video; receive input data from the plurality of input sources; monitor the received input data for one or more data patterns indicated by input-selection criteria, wherein the one or more data patterns comprise: (a) at least one data pattern that corresponds to implicit information that is indicative of desired content for the multimode input field and (b) at least one data pattern corresponding to an explicit input-content instruction that indicates desired content for the multimode input field; select at least one input source from the plurality of input sources in response to detection of a data pattern in the received input data, wherein the detected data pattern matches a corresponding one of the data patterns indicated by the input-selection criteria; and display content in the multimode input field, wherein the displayed content is based on input data received from the at least one selected input source.