GestureController.goto (): fix progress check

[lenemter]

Fixes #2724 for me

I think what's happening here is:

1. We're calling goto multiple times per frame with 0 (show) then 1 (hide)
2. Sometimes when the switch from 0 to 1 happens, current progress is 1 (because the dock is hidden), but the timeline exists and it's changing the progress to 0

[leolost2605]

Ah yes that makes so much sense! I noticed the same thing when investigating the active workspace in the mtv sometimes being wrong and fixed it in #2787 but ig i shouldve made it a separate pr