Remember the last used download directory.

Thanks to @Carpetsmoker for the original PR.

Closes #745.
Closes #37.

doc/help/settings.asciidoc

@@ -123,6 +123,7 @@
 |==============
 |Setting|Description
 |<<storage-download-directory,download-directory>>|The directory to save downloads to. An empty value selects a sensible os-specific default. Will expand environment variables.
+|<<storage-remember-download-directory,remember-download-directory>>|Whether to remember the last used download directory.
 |<<storage-maximum-pages-in-cache,maximum-pages-in-cache>>|The maximum number of pages to hold in the global memory page cache.
 |<<storage-object-cache-capacities,object-cache-capacities>>|The capacities for the global memory cache for dead objects such as stylesheets or scripts. Syntax: cacheMinDeadCapacity, cacheMaxDead, totalCapacity.
 |<<storage-offline-storage-default-quota,offline-storage-default-quota>>|Default quota for new offline storage databases.
@@ -1108,6 +1109,17 @@ The directory to save downloads to. An empty value selects a sensible os-specifi
 
 Default: empty
 
+[[storage-remember-download-directory]]
+=== remember-download-directory
+Whether to remember the last used download directory.
+
+Valid values:
+
+ * +true+
+ * +false+
+
+Default: +pass:[true]+
+
 [[storage-maximum-pages-in-cache]]
 === maximum-pages-in-cache
 The maximum number of pages to hold in the global memory page cache.

qutebrowser/browser/downloads.py

@@ -48,13 +48,21 @@ ModelRole = usertypes.enum('ModelRole', ['item'], start=Qt.UserRole,
 
 RetryInfo = collections.namedtuple('RetryInfo', ['request', 'manager'])
 
+# Remember the last used directory
+_last_used_directory = None
+
 
 def _download_dir():
     """Get the download directory to use."""
     directory = config.get('storage', 'download-directory')
-    if directory is None:
-        directory = standarddir.download()
-    return directory
+    remember_dir = config.get('storage', 'remember-download-directory')
+
+    if remember_dir and _last_used_directory is not None:
+        return _last_used_directory
+    elif directory is None:
+        return standarddir.download()
+    else:
+        return directory
 
 
 def _path_suggestion(filename):
@@ -433,6 +441,7 @@ class DownloadItem(QObject):
             filename: The full filename to save the download to.
                       None: special value to stop the download.
         """
+        global _last_used_directory
         if self.fileobj is not None:
             raise ValueError("fileobj was already set! filename: {}, "
                              "existing: {}, fileobj {}".format(
@@ -448,6 +457,8 @@ class DownloadItem(QObject):
             # try again.
             self._create_full_filename(os.path.join(_download_dir(), filename))
 
+        _last_used_directory = os.path.dirname(self._filename)
+
         log.downloads.debug("Setting filename to {}".format(filename))
         if os.path.isfile(self._filename):
             # The file already exists, so ask the user if it should be

qutebrowser/config/configdata.py

@@ -557,6 +557,10 @@ def data(readonly=False):
              "sensible os-specific default. Will expand environment "
              "variables."),
 
+            ('remember-download-directory',
+             SettingValue(typ.Bool(), 'true'),
+             "Whether to remember the last used download directory."),
+
             ('maximum-pages-in-cache',
              SettingValue(
                  typ.Int(none_ok=True, minval=0, maxval=MAXVALS['int']), ''),