Posting this here if people look for it, because it looks like there wasn't a mention of this behavior change in the release notes / "what's new" documentation (or at least any I can find). I created an SR for this, SR01336655-01, but now the behavior aligns with what's documented in the User Guide so it was closed without action.

User Guide Link: 

Previously (2025x GA and before), you could drag and drop a widget onto the "+" New Tab icon next to the open tabs to move that widget to a new tab. This feature was removed in 2025X FD01 without mention.

The "workaround" is using the "move widget to new tab" button that's available in the widget thumbnail previews when hovering over a tab. That's nice, because you can also assign a hotkey to it. But I found it a little frustrating to see the drag and drop behavior change without explanation or notice. 

Anyway, hopefully having this searchable is useful somehow. 

Perhaps someone knowledgeable within DS can share some insight on why that drag and drop feature was removed, or maybe it was an oversight and not intentional.