Bug 1932594 Comment 6 Edit History

Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.

Original comment by
on 
The issue here is in on_drop.
When the action is `GROUP_DROP_ACTION_CREATE` and we have `dropIndex` we move the dragged tab before we call `gBrowser.addTabGroup`
in this case `groupTab` index is no longer valid.

The fix is simply to assign `groupTab` before we move any tab.

```diff
          this._finishAnimateTabMove();
+         let groupTab = this.allTabs[groupDropIndex];
          if (groupDropAction == GROUP_DROP_ACTION_APPEND) {
-           let groupTab = this.allTabs[groupDropIndex];
            groupTab.group.addTabs(movingTabs);
          } else if (dropIndex !== false) {
            for (let tab of movingTabs) {
              gBrowser.moveTabTo(tab, dropIndex);
              if (incrementDropIndex) {
                dropIndex++;
              }
            }
          }
          if (groupDropAction == GROUP_DROP_ACTION_CREATE) {
-           let groupTab = this.allTabs[groupDropIndex];
            gBrowser.addTabGroup([groupTab, ...movingTabs], {
              insertBefore: draggedTab,
              showCreateUI: true,
              color: draggedTab._dragData.tabGroupCreationColor,
            });
          }
        }
```
Revision 1 by
on 
The issue here is in on_drop.
When the action is `GROUP_DROP_ACTION_CREATE` and we have `dropIndex` we move the dragged tab before we call `gBrowser.addTabGroup`
in this case `groupTab` index is no longer valid.

The fix is simply to assign `groupTab` before we move any tab.

```diff
          this._finishAnimateTabMove();
+         let groupTab = this.allTabs[groupDropIndex];
          if (groupDropAction == GROUP_DROP_ACTION_APPEND) {
-           let groupTab = this.allTabs[groupDropIndex];
            groupTab.group.addTabs(movingTabs);
          } else if (dropIndex !== false) {
            for (let tab of movingTabs) {
              gBrowser.moveTabTo(tab, dropIndex);
              if (incrementDropIndex) {
                dropIndex++;
              }
            }
          }
          if (groupDropAction == GROUP_DROP_ACTION_CREATE) {
-           let groupTab = this.allTabs[groupDropIndex];
            gBrowser.addTabGroup([groupTab, ...movingTabs], {
              insertBefore: draggedTab,
              showCreateUI: true,
              color: draggedTab._dragData.tabGroupCreationColor,
            });
          }
        }
```
you can also apply `gBrowser.addTabGroup([groupTabFixed, ...movingTabs].sort((a,b) => a._tPos - b._tPos)` to fix bug 1933210

Back to Bug 1932594 Comment 6