Responsive LiveSearch toolbar item is rendered no matter access restriction
This is a result of a rather large work on trying to make the TYPO3 backend custom for a project.
The backend layout file Main.html (EXT:backend/Resources/Private/Templates/Backend/Main.html) contains a rendering of a LiveSearchToolbarItem even though a person might not have access
<button class="topbar-button topbar-button-search t3js-topbar-button-search"> <core:icon identifier="actions-search" alternativeMarkupIdentifier="inline" /> </button>
This causes the search to be printed in responsive view. Since you don't have access to the toolbar item (checkAccess() method from ToolbarItemInterface) you don't get a printed LiveSearch to use.
This part of ToolbarItem rendering (including the User Settings wrench icon) could be grouped into a viewhelper to render avaialble toolbar items. Perhaps introduce a rendering API for such things (a section in Fluid, or whatever ways the rendering of the backend is going)