When using the vertical tabs sidebar, if a tab is closed and then the close is undone (via CMD + SHIFT + T or CMD + Z), the tab should reappear. Instead, what often happens is that instead of the closed tab reappearing, ANOTHER tab disappears. The tab count shown in the vertical toolbar is still technically correct, but the actual tabs shown are incorrect as one or more tabs are missing from the list.
Please watch the video for a demonstration. In the video, first I open up a total of 13 tabs. At this point, when 13 tabs are open, the ONLY actions I am taking on the tabs are closing (CMD + W) and reopening (CMD + SHIFT + T) . You can see the issue appear immediately. 13 tabs are open. CMD+W closes the open tab and therefore that tab disappears from the list and the number of open tabs updates to 12 - this is correct. The next thing I do is hit CMD + SHIFT + T, which should reopen the last closed tab, but instead, it makes two additional tabs disappear from the tab list and does not reappear the last closed tab, although the count of tabs correctly updates back to 13. This sequence of closing tabs and trying to reopen them continues throughout the video, and you can see more and more tabs disappear from the list as I try to reopen closed tabs. At the end of the video, I change from vertical tabs to horizontal tabs and back to vertical, at which point the proper tabs all reappear in the vertical sidebar.
When a closed tab is "undone", the tab should reappear in the vertical list, and no additional tabs should disappear.
The last few updates to Orion feel like a significant regression, I am encountering so many new bugs (this one and the 1Password bugs that I reported already, among others).
Version 0.99.131-rc (WebKit 621.1.2.111.4)
Sequoia (15)