Previously when markers were used, the newly introduced clamping code (#104516) would stop the last channel from being shown.
This patch fixes that by modifying the `v2d->tot.ymin` calculation.
This is a bit counterintuitive since the `v2d->tot` height is calculated in `action_draw.c`. But the advantage of doing it there is that it also works for the channels region.
Pull Request #104892
4ab91dc0c9