Allow controlling the Virtual library with calibre://search URLs

manual/url_scheme.rst

@@ -81,6 +81,18 @@ search expression is complicated, :ref:`encode it as a hex string <hex_encoding>
 and use ``eq`` instead. Leaving out the query will cause the current search to
 be cleared.
 
+By default, if a Virtual library is selected, calibre will clear it before
+doing the search to ensure all books are found. If you want to preserve the
+Virtual library, use::
+
+    calibre://search/Library_Name?q=query&virtual_library=_
+
+If you want to switch to a particular Virtual library, use::
+
+    calibre://search/Library_Name?virtual_library=Library%20Name
+
+replacing spaces in the Virtual library name by ``%20``.
+
 
 .. _hex_encoding:
 

src/calibre/gui2/ui.py

@@ -718,8 +718,13 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
                 if sq:
                     sq = sq[0]
             sq = sq or ''
+            vl = (query.get('virtual_library') or ['-'])[0]
+            if vl == '-':
+                vl = None
 
             def doit():
+                if vl != '_':
+                    self.apply_virtual_library(vl)
                 self.search.set_search_string(sq)
             self.perform_url_action(library_id, library_path, doit)