Hi MOHAMAD GHOUL, First thank you for posting about this, alot of errors reported by users have helped improved the product over time. However this was not a feature that has changed, that I know of.

In order to move a group you can move a tile representing a webpage outside of its current group. https://support.mozilla.org/en-US/kb/tab-groups-organize-tabs

Was this an add on feature? I may be wrong as well, I do not personally use tabbed groups alot. Would you mind showing a screenshot of this feature? How do I create a screenshot of my problem? Install an older version of Firefox if you need that as well.

Thank you.

Hello guigs2

Thank you for your reply, your above solution is good for moving tabs from group to other group,

My Firefox usage is for multiple categorized tab groups, I was using all the tabs on one group but doing a categorize groups ease the reference,

Firefox feature address bar is useful for search and look up tabs also, when using Firefox with more than 100 tabs there must be many categories of website tabs groups.

The above issue suddenly happened when moving tabs and using Java and Flash plugins at the same time, Your reply was helpful enough, Thanking your cooperation,

I'm proud to use Firefox browser and proud to use this community also for future updates and stay tuned to mozilla support center,

Best Regards

MOHAMAD GHOUL