Prerequisites:
Must in the game world on a system that can support post-processing shaders (Super Secret Settings)

Procedure:

1. Use the Super Secret Settings button in the Options menu. This will cycle through a hidden list of post-processing shaders and turn shaders on, making wierd visual effects to happen on the screen.
2. Now, you can press F4. This will toggle your shader on and off.
3. Press F5. This will cycle through your perspective and revert to the default shader mode (no shader.)
4. Press F4 again. Whie this should turn the shader back on, in actuality, it doesn't do anything because, instead of turning the shader off, F5 sets it to be the default (no shader) mode.

The Issue
When you use the Super Secret Settings button again, instead of either turning on the shader that was on in the first place or turning on the first shader in the list, it instead cycles to the next shader in the list following the most recent one used. If the player wants to return to the shader they were on in the first place, they are forced to cycle through the whole list of shaders. This takes a long time, so players who often use F5 mode can't properly use shaders how they might want them to be used.

The Solution

1. Replace the Super Secret Settings button with a list menu like the texture pack menu. I believe this is something currently being worked on, but I know it will take some time and it won't fully solve the given issue; While it will be slightly less inconvenient, it will still be annoying to have to go to a menu every time you press F5.
2. Change the F5 function to turn off the shader instead of setting the current shader to default. This allows players to turn back their shader immediately after they change perspective, which is most likely something that can be considered "good enough" by players.
3. Allow players the option to make shaders not be disabled when perspective is changed. This option is very convenient for players who don't spend much time in Spectator mode.