Bugzilla

_As a user who rearranges tabs by dragging and dropping them, I want to disable the creation of tab groups by dragging and dropping, so that I can avoid accidentally creating unwanted groups when I am rearranging my tabs. _

**Context:** 
Some users continue to report being frustrated by the accidental creation of tab groups while dragging a tab to change its placement. Telemetry data supports this: in November, about 4.7% of tab groups created by drag-and-drop were immediately canceled. We sought to improve this functionality in https://bugzilla.mozilla.org/show_bug.cgi?id=1942332, yet some people still find it too easy to accidentally create a tab group via drag-and-drop, whereas others find it too hard to do so. Because it is challenging to configure the drag-and-drop sensitivity to be optimal for all users, a simple preference toggle can enable those who don't want the functionality to turn it off. When the setting is disabled, users will still be able to create tab groups through the context menu.

**Acceptance criteria:**
- a preference exists in about:settings to let users disable the drag-and-drop method of tab group creation
- when the drag-and-drop method is disabled, a user will not be able to create a tab group by dragging one or more tabs onto another tab 
- by default, the drag-and-drop method is enabled

_As a user who rearranges tabs by dragging and dropping them, I want to disable the creation of tab groups by dragging and dropping, so that I can avoid accidentally creating unwanted groups when I am rearranging my tabs._

**Context:** 
Some users continue to report being frustrated by the accidental creation of tab groups while dragging a tab to change its placement. Telemetry data supports this: in November, about 4.7% of tab groups created by drag-and-drop were immediately canceled. We sought to improve this functionality in https://bugzilla.mozilla.org/show_bug.cgi?id=1942332, yet some people still find it too easy to accidentally create a tab group via drag-and-drop, whereas others find it too hard to do so. Because it is challenging to configure the drag-and-drop sensitivity to be optimal for all users, a simple preference toggle can enable those who don't want the functionality to turn it off. When the setting is disabled, users will still be able to create tab groups through the context menu.

**Acceptance criteria:**
- a preference exists in about:settings to let users disable the drag-and-drop method of tab group creation
- when the drag-and-drop method is disabled, a user will not be able to create a tab group by dragging one or more tabs onto another tab 
- by default, the drag-and-drop method is enabled