Comment 0 for bug 1930912

1. Open the main calibre program.
2. Double-click on "Quick Start Guide" to open it in E-book viewer.
3. Press Ctrl+f to open the viewer's Search pane.
4. Type "abc123"(no quotes) in the Search input field and press Enter. A warning window saying "No matches were found for: abc123" pops up. Close the warning window.
5. Right-click in the input field, a context menu shows up. Click on "Clear search history".
6. Close the E-book viewer.
7. Click on "Preferences -> Searching -> Clear search histories" in the main calibre program.
8. Close the main calibre program.

%APPDATA%/calibre/viewer-webengine.json still contains "abc123", in this piece:

  "saved-search-settings": {
    "abc123": {
      "case_sensitive": false,
      "mode": "normal"
    }
  },

Calibre version: 5.20,
OS: Windows 10 Home 1803.