If we leave trigger position centered then 50% of the screen will always be blank when in fast mode and using post priority. Still your idea has some merit if we stop acquisitions and use pan/zoom to look closer at the waveform. Typical usage for post priority however is likely to be digital waveforms where the user is attempting to decipher some communication protocol. In this context, fast mode is less relevant. Fast mode is appropriate when we need a “high definition” acquisition of a single complex signal.
If we agree that comparing for equality is the primary use for a reference wave then any feature that compromise this should not be default. In this context I think the current behavior is appropriate and so this implies additional controls are needed for the added features.
Again, I appreciate your input so will keep this in mind for future updates.