Add option to always show tab bar - even with only one single tab

[themilkman]

Problem description

Sometimes I accidentally drag&drop one of my SM tabs and thus it opens in a new window. I cannot simply put it back as the new window has no tab bar - and so no tab to drag. If the original window had only two tabs it makes the thing even more "complicated" to resolve without closing & reopening the repo - which is not desired.

Preferred solution

Add an option to always show the tab bar.

Alternatives

Maybe add an option to disable drag&drop into new window.

[srbs]

duplicates: #848

[themilkman]

duplicates: #848

Thanks, did not find it.