I know support for IR transmission is currently quite limited, but it'd be quite useful if you could 'learn' a button from a remote, and then retransmit that when a different button is pressed.
The specific use case is to have one remote with all media buttons mapped for kodi, which obviously currently possible. What's missing is the ability to map the power button on the remote to an arbitrary IR transmit sequence on the Flirc dongle - this would allow it to be mapped to the IR sequence of the TV remote, doing away with the need for two remotes.
An additional case would be to make it so you could make the volume buttons control the AV reviewer, not the instance of kodi. This could work well with the "long keypress" feature, so a normal press on the power/volume will be blasted to the TV/AV receiver, whereas a long press could be mapped to kodi.