Difficult to step just a single frame in VLC 4

In VLC 2, "next frame" was quite slow, so you could easily step frames by tapping "E". In VLC 4, you almost get full playback speed when holding "E" and you almost can't tap quickly enough to step a single frame.

Suggest to make the delay after pressing "E" the first time several hundred milliseconds, and then after that the delays can be as short as possible.

VLC version 4.0.0-dev Otto Chriek (4.0.0-dev-565-g7cf5d92e)