Tab not in group are not well managed

[gagarine]

Simple Tab Group manages poorly tabs not in a group but only attached to a window. This can easily lead to tabs lost. This is not acceptable for a "stable" version.

Safari handle this in a much better way. I believe STG should copy Safari behavior if possible.

Allow switching back to the original tab of the windows Tabs not in a group should be linked only to the current windows. They should not be visible in any way from another window. Switching to a group from a window with tab open should create a "special group" (but don't call it group, just "tabs") only visible from this window. This allows the user to switch back to the tabs open before it opened the group.

This is how the Safari UI handle this. The "watching" group is open, and I can switch back to the 4 tabs that was in this window before I switched to the "watching" group.

Alert user before closing "ungrouped" tab When a user is on a group with a window that had previously tab open, simply alert the user if he tries to close the windows.

Windows and group should be independent When a group is already open, selecting it in STG from another windows switch to the windows that have this group open.

Instead, it should open the tab of this group in the current windows. The group is then opened twice. Safari mirror tab opening/closing/moving but load content only on the active group. It then swap the content if you change from one windows to the other.

This is not multiple bugs but the general behavior logic. And it's definitely a UI bug has the current behavior can easily lead to tab lost.