Regression WStackedWidget in layout with overflow can lose scrollbar on animated transition
With github wt 4.0.5-52-ge490cdd9, a WStackedWidget in a layout can lose scrollbars on animated transitions. I believe this is a regression introduced in 4.0.5-8-gf933d073 while fixing #6788.
The attached test program demonstrates the issue. Press the button to toggle the WStackedWidget between two containers with text. On the second toggle, the scrollbar will disappear.
The issue will not occur if the transition animation is disabled or if the WStackedWidget.js change in 4.0.5-8-gf933d073 is reverted.
Partially reverting the patch in 4.0.5-8-gf933d073 seems to address this issue, while still maintaining correct behavior for the wt-homepage issue reported in #6788. I'm not sure if that's the best fix, but I've attached a patch for your review.