"not var:abc" does not work as tab_bar_filter

**Describe the bug** As tabbar filter, "not var:abc" does not filter out tabs with abc var set. **To Reproduce** 1. Launch a new tab with abc var set 2. Update tab_bar_filter to "var:abc", it correctly displays the newly launched tab as well as current active one, but updating it to `tab_bar_filter not var:abc`, every tab is displayed.