SUMMARY The "Toggle Filter Bar" on the toolbar does not toggle, it only makes the filter bar appear if it's not shown. STEPS TO REPRODUCE AND OBSERVED RESULTS AGAINST EXPECTED RESULTS: 1. With the Filter bar non visible, click on the Filter button on the toolbar. The filter bar appears as expected 2. Click again on the button to close the bar, the bar stays opened. EXAMPLE OF WORKING TOGGLE BUTTON: This behavior works as expected with the search bar. Clicking on the "Toggle Seach bar" button will make the search bar appear if not showing, and disappear if showing.
*** Bug 449616 has been marked as a duplicate of this bug. ***
By the way, about the search bar: clicking on the icons toggles it, but pressing Ctrl+F shortcut doesn't toggle — it's the same as for filter bar.
A "Toggle Filter Bar" action is included since release 21.04 (commit https://invent.kde.org/system/dolphin/-/commit/60b9eaa4c1c4d3057934d2cefbbe986553090ab3), and works as expected, toggling the filter bar on and off. There is also a "Show Filter Bar" action which just shows the filter bar. This is necessary to keep the keyboard workflow many users are used to. Unfortunately, the "Show" action was also mistakenly named as "Toggle", which causes the understandable confusion. This name has been fixed (commit https://invent.kde.org/system/dolphin/-/commit/1939609e703b89d7e2c06514e373857ff2bc925b) and will be released on 22.04.