If you drag the App Search Tool too high in the editor, its draggable header can disappear behind the top menubar. Once that happens, you can't grab it to move it again. The tool's position also persists across sessions, so simply closing and reopening the editor won't reset it.
What you might notice
The App Search Tool is visible but can't be moved or repositioned
The drag bar at the top of the tool is hidden behind the editor's top menubar
The issue persists after closing and reopening the editor
Workaround
To reset the tool's position, try one of the following:
Clear your browser's cache and cookies, then reload the editor
Open the editor in a new session — Incognito mode, a different browser, or a full browser restart will all work
Status
Because a workaround is available and this is an uncommon occurrence, it's not currently a high priority — but it's on our radar for the longer term.