This happens when setting track visibility from ReaScript and minimizing/maximizing REAPER window:
(EDIT: zooming or any other user action in the arrange view also refreshes the scrollbars)
AFAIK there isn't a way to refresh scroll bars?
I think that when calling these...
Code:
boolean reaper.SetMediaTrackInfo_Value(track, "B_SHOWINMIXER", newvalue)
boolean reaper.SetMediaTrackInfo_Value(track, "B_SHOWINTCP", newvalue)
...the arrange view scroll bars (and TCP) should be refreshed.
Related FR -
SetTCPscroll:
https://forum.cockos.com/showthread....58#post1961658