Sequencer: add fail-safe to Set Playback buttons

Hi, The Set Playback Start/End buttons in Sequencer are right next to the To Front and To End buttons. I find myself missing the To Start button by a few millimeters and setting the start of my sequence to the final frame. Then it take me a moment to realize when I can’t rewind it. Then I have to fix it.

This could be easily solved by adding a fail-safe of requiring the Set Start/End buttons to be Alt-clicked. Thanks for considering my request.