Add helper function to browse for root directory

Re #3020

spinetoolbox/helpers.py

@@ -954,6 +954,22 @@ def select_certificate_directory(parent, line_edit):
     line_edit.setText(answer)
 
 
+def select_root_directory(parent, line_edit):
+    """Shows file browser and inserts selected root directory to given line edit.
+    Used in Tool Properties.
+
+    Args:
+        parent (QWidget, optional): Parent of QFileDialog
+        line_edit (QLineEdit): Line edit where the selected path will be inserted
+    """
+    current_path = get_current_path(line_edit)
+    initial_path = current_path if current_path is not None else home_dir()
+    answer = QFileDialog.getExistingDirectory(parent, "Select root directory", initial_path)
+    if not answer:
+        return
+    line_edit.setText(answer)
+
+
 def get_current_path(le):
     """Returns the text in the given line edit. If no text, returns the
     placeholder text if it is a valid path. If it's not a valid path,

spinetoolbox/widgets/settings_widget.py

@@ -168,14 +168,14 @@ def read_settings(self):
         snap_entities = self._qsettings.value("appSettings/snapEntities", defaultValue="false")
         merge_dbs = self._qsettings.value("appSettings/mergeDBs", defaultValue="true")
         db_editor_show_undo = int(self._qsettings.value("appSettings/dbEditorShowUndo", defaultValue="2"))
-        max_ent_dim_count = int(self.qsettings.value("appSettings/maxEntityDimensionCount", defaultValue="5"))
-        build_iters = int(self.qsettings.value("appSettings/layoutAlgoBuildIterations", defaultValue="12"))
-        spread_factor = int(self.qsettings.value("appSettings/layoutAlgoSpreadFactor", defaultValue="100"))
-        neg_weight_exp = int(self.qsettings.value("appSettings/layoutAlgoNegWeightExp", defaultValue="2"))
+        max_ent_dim_count = int(self._qsettings.value("appSettings/maxEntityDimensionCount", defaultValue="5"))
+        build_iters = int(self._qsettings.value("appSettings/layoutAlgoBuildIterations", defaultValue="12"))
+        spread_factor = int(self._qsettings.value("appSettings/layoutAlgoSpreadFactor", defaultValue="100"))
+        neg_weight_exp = int(self._qsettings.value("appSettings/layoutAlgoNegWeightExp", defaultValue="2"))
         if commit_at_exit == 0:  # Not needed but makes the code more readable.
             self.ui.checkBox_commit_at_exit.setCheckState(Qt.CheckState.Unchecked)
         elif commit_at_exit == 1:
-            self.ui.checkBox_commit_at_exit.setCheckState(Qt.PartiallyChecked)
+            self.ui.checkBox_commit_at_exit.setCheckState(Qt.CheckState.PartiallyChecked)
         else:  # commit_at_exit == "2":
             self.ui.checkBox_commit_at_exit.setCheckState(Qt.CheckState.Checked)
         self.ui.checkBox_entity_tree_sticky_selection.setChecked(sticky_selection == "true")