Emulator

Read-only mode is important in the making of tool-assisted recordings (.DTM recordings). With it, you can check what the section you just played looks like and whether it syncs at all. But Read-only mode has been broken ever since it was implemented.

How it's supposed to work:
While in read-only mode, you can load a savestate from the current movie you are recording and it will play back the movie's input from that frame on, until the movie ends. For example, I'm recording a .DTM and save a state in the main menu of a game, now I'm elsewhere and load the state read-only mode and dolphin is now supposed to bring me there.

Dolphin works like this right now:
After loading a state from the current movie in read-only mode, like in the example above, Dolphin doesn't play back input but instead records new input from that point. So it's basicly like "Read & Write" mode, the opposite of Read-only mode. As far as I'm aware, Dolphin will only play back input upon loadstate if the .DTM has been selected to play back and read-only mode was "on" from power-on.

Another problem is that you aren't allowed to start recording a movie if read-only mode is active (before emulation begins). However, it shouldn't matter at all. You should be able to switch between Read-only mode and Read & Write mode at will, preferably by pressing a hotkey.

To clarify, this is how read-only works:
Recording a movie, save a state, keep playing, load the state (read-only is active), the emulator is supposed to play back the movie after loading the state until the current point.

To clarify, this is how read & write works:
Recording a movie, save a state, keep playing, load the state (read&write was active), the emulator is supposed to record new input after loading the state.

For bonus points, Dolphin should preferably show - in the status bar or onscreen, besides the frame count - whether it is in read-only mode or read & write mode.