GUI: when opening the index, discriminate errors on the main index from errors on external ones, to avoid starting the initial indexing dialog in the latter case

website/BUGS.html

@@ -37,33 +37,35 @@
 
       <h2><a name="b_latest">recoll 1.15</a></h2> 
 
-        <ul> 
+      <ul> 
+
+        <li>Cancelling a preview in the GUI will also cancel the indexing
+          thread if it is running.</li>
 
         <li>Using search preview while the indexing thread is running will
-          sometimes crash the GUI or provoke other strangeness. This
-          is due to insufficient protection of resources shared by
-          several threads. The current and unsatisfying workaround, is
-          to avoid the situation, for example by using the standalone
-          recollindex program instead of the GUI indexing thread. I
-          will be working on a program-wide cleanup of multithreaded
-          operation for the next version.</li>
+          sometimes crash the GUI or provoke other strangeness. This is
+          apparently due to insufficient protection of resources shared by
+          several threads. After recent cleanup, the problem occurs quite
+          seldom but it is not completely gone. The current and
+          unsatisfying workaround, is to avoid the situation, for example
+          by using the standalone recollindex program instead of the GUI
+          indexing thread.</li>
 
         <li>The operations on the parent document in the result list
 	  right click menu (Preview and Open), do not work, they
 	  access the file's parent directory instead.</li>
 
         <li>The rclzip filter can't handle utf-8 in path names for archive
-        members. An  <a
-        href="http://www.recoll.org/filters/rclzip">updated filter</a> is
-        available. </li>
+          members. An <a href="http://www.recoll.org/filters/rclzip">
+            updated filter</a> is available. </li>
 
         <li>The rclzip and rclchm filters can't handle archive members
-        with a colon (':') in the file name or path. The files are normally
-        indexed and can be searched for, but they can't be displayed
-        (neither opened nor previewed). There is a <a
-        href="https://bitbucket.org/medoc/recoll/changeset/3751ea8ea179">
-        patch</a> which fixes the issue (then needs full reindex for these
-        files).</li>
+          with a colon (':') in the file name or path. The files are normally
+          indexed and can be searched for, but they can't be displayed
+          (neither opened nor previewed). There is a 
+          <a href="https://bitbucket.org/medoc/recoll/changeset/3751ea8ea179">
+            patch</a> which fixes the issue (then needs full reindex for these
+          files).</li>
 
         <li>After an upgrade, the recoll GUI sometimes crashes on
           startup. This is fixed by removing (back it up just in case)