Icon of closed window blocking active window to take its spot in the taskbar

I could reproduce it, and will try to come up with a fix.

Meanwhile, a simpler workaround using the option "Drag within/between groups using right mouse button":

When the console window closes, right click and drag the second Firefox button out of the taskbar. Then, drag the button onto the pinned item.

I've looked at the issue, and I believe fixing it isn't worth the effort.

The flaw with the pinned item is not the only issue.

Try to right click the second Firefox window. Explorer thinks that it's not pinned, and will allow you to pin it. You can pin it, and you'll have two pinned icons of Firefox. Then wired things start happening, like a pinned item which can't be removed.

I believe the jump list can go out of sync, too. I haven't checked this one, though.

All this happens because explorer was designed with one-AppId = one-group in mind.

Internally, explorer has the following objects: task, task group, button, button group.

With Firefox and console open, explorer uses one task group, two tasks, one button group, and two buttons.

When you disable grouping with the tweaker, explorer uses two instances of each object. And because the task group contains information about the pinned item, the jump list, etc., things can go wrong.

Now the ideal solution here is to have one task group, and two of the rest objects. Then the information will be shared. But explorer expects to have no more than one button group of the same task group on the taskbar, and changing that would be a major task.

The workaround you've mentioned works because the tweaker actually removes and puts back all the taskbar buttons to apply the changes. When the Firefox window is put back, explorer sees that there's a matching pinned item, and puts it in that location.

I'll leave this bug report open, and maybe I'll get back to it one day.

P.S. Sorry for writing so much, I didn't think the comment would turn out so long O_o.

Thank you for this explanation and I can understand the problem

As another workaround: Would it be possible to add a group/ungroup-toggle as an action for the new mouse button control events?

And maybe combine/uncombine too, if somebody wants to temporarily save space in the taskbar.