Changing the toolbar state to activate icon display turns out to be difficult - scripts which which use System Events seem to work fine if launched from the Scripts menu, but freeze if they are launched from the toolbar.

Another approach, however, (see another post for a first draft of a one-click search), is to bypass the search bar and get the script to throw up a dialog into which you can type your search string directly, before it clears focus and filters and selects the Inbox and Library trees.

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