diff --git a/CHANGELOG.md b/CHANGELOG.md
index 59a97711..698b8eb0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,11 @@ CHANGELOG for FlatCAM beta
 - solved a Shapely 2.0 deprecation warning
 - more Qt6 port bugs fixed
 - in Autolevelling Plugin modified the UI; work in progress - the frame disable is not working
+- in Excellon Editor and Geometry Editor solved some Shapely 2.0 deprecation warnings
+- in Excellon Editor made sure that the tool diameter is always updated before adding a new drill (or drill array)
+- changing units is not possible while in Editors
+- changing units outside the Preferences will make no permanent changes
+- deleting all shapes from the shapes collection (OpenGl graphics) will reset also the index in the collection data dict
 
 25.09.2021
 
diff --git a/appEditors/AppExcEditor.py b/appEditors/AppExcEditor.py
index 28777b8e..306ce018 100644
--- a/appEditors/AppExcEditor.py
+++ b/appEditors/AppExcEditor.py
@@ -91,7 +91,7 @@ class SelectEditorExc(FCShapeTool):
 
             # constrain selection to happen only within a certain bounding box; it works only for MultiLineStrings
             if isinstance(closest_shape.geo, MultiLineString):
-                x_coord, y_coord = closest_shape.geo[0].xy
+                x_coord, y_coord = closest_shape.geo.geoms[0].xy
                 delta = (x_coord[1] - x_coord[0])
                 # closest_shape_coords = (((x_coord[0] + delta / 2)), y_coord[0])
                 xmin = x_coord[0] - (0.7 * delta)
@@ -272,6 +272,8 @@ class DrillAdd(FCShapeTool):
         return DrawToolUtilityShape(self.util_shape(data))
 
     def util_shape(self, point):
+        self.selected_dia = self.draw_app.tool2tooldia[self.draw_app.last_tool_selected]
+
         if point[0] is None and point[1] is None:
             point_x = self.draw_app.x
             point_y = self.draw_app.y
@@ -287,7 +289,7 @@ class DrillAdd(FCShapeTool):
         return MultiLineString([(start_hor_line, stop_hor_line), (start_vert_line, stop_vert_line)])
 
     def make(self):
-
+        self.selected_dia = self.draw_app.tool2tooldia[self.draw_app.last_tool_selected]
         try:
             QtGui.QGuiApplication.restoreOverrideCursor()
         except Exception:
@@ -525,6 +527,8 @@ class DrillArray(FCShapeTool):
         return circular_geo
 
     def util_shape(self, point):
+        self.selected_dia = self.draw_app.tool2tooldia[self.draw_app.last_tool_selected]
+
         if point[0] is None and point[1] is None:
             point_x = self.draw_app.x
             point_y = self.draw_app.y
@@ -540,6 +544,7 @@ class DrillArray(FCShapeTool):
         return MultiLineString([(start_hor_line, stop_hor_line), (start_vert_line, stop_vert_line)])
 
     def make(self):
+        self.selected_dia = self.draw_app.tool2tooldia[self.draw_app.last_tool_selected]
         self.geometry = []
         geo = None
 
@@ -1609,7 +1614,11 @@ class MoveEditorExc(FCShapeTool):
     def selection_bbox(self):
         geo_list = []
         for select_shape in self.draw_app.get_selected():
-            geometric_data = select_shape.geo
+            if isinstance(select_shape.geo, (MultiLineString, MultiPolygon)):
+                geometric_data = select_shape.geo.geoms
+            else:
+                geometric_data = select_shape.geo
+
             try:
                 for g in geometric_data:
                     geo_list.append(g)
@@ -2921,7 +2930,7 @@ class AppExcEditor(QtCore.QObject):
                     # all x.geo in self.storage_dict[storage] are MultiLinestring objects for drills
                     # each MultiLineString is made out of Linestrings
                     # select first Linestring object in the current MultiLineString
-                    first_linestring = x.geo[0]
+                    first_linestring = x.geo.geoms[0]
                     # get it's coordinates
                     first_linestring_coords = first_linestring.coords
                     x_coord = first_linestring_coords[0][0] + (float(first_linestring.length / 2))
@@ -3638,22 +3647,19 @@ class AppExcEditor(QtCore.QObject):
 
     def draw_utility_geometry(self, geo):
         # Add the new utility shape
+
+        if isinstance(geo.geo, (MultiLineString, MultiPolygon)):
+            util_geo = geo.geo.geoms
+        else:
+            util_geo = geo.geo
+
         try:
             # this case is for the Font Parse
-            for el in list(geo.geo):
-                if type(el) == MultiPolygon:
-                    for poly in el:
+            for el in util_geo:
+                if isinstance(el, (MultiLineString, MultiPolygon)):
+                    for sub_geo in el.geoms:
                         self.tool_shape.add(
-                            shape=poly,
-                            color=(self.app.defaults["global_draw_color"] + '80'),
-                            update=False,
-                            layer=0,
-                            tolerance=None
-                        )
-                elif type(el) == MultiLineString:
-                    for linestring in el:
-                        self.tool_shape.add(
-                            shape=linestring,
+                            shape=sub_geo,
                             color=(self.app.defaults["global_draw_color"] + '80'),
                             update=False,
                             layer=0,
@@ -3665,12 +3671,15 @@ class AppExcEditor(QtCore.QObject):
                         color=(self.app.defaults["global_draw_color"] + '80'),
                         update=False,
                         layer=0,
-                        tolerance=None
-                    )
+                        tolerance=None)
         except TypeError:
             self.tool_shape.add(
-                shape=geo.geo, color=(self.app.defaults["global_draw_color"] + '80'),
-                update=False, layer=0, tolerance=None)
+                shape=util_geo,
+                color=(self.app.defaults["global_draw_color"] + '80'),
+                update=False,
+                layer=0,
+                tolerance=None)
+        # print(self.tool_shape.data)
         self.tool_shape.redraw()
 
     def replot(self):
@@ -3718,23 +3727,29 @@ class AppExcEditor(QtCore.QObject):
         if geometry is None:
             geometry = self.active_tool.geometry
 
+        if isinstance(geometry, (MultiLineString, MultiPolygon)):
+            use_geometry = geometry.geoms
+        else:
+            use_geometry = geometry
+
         try:
-            for geo in geometry:
+            for geo in use_geometry:
                 plot_elements += self.plot_shape(geometry=geo, color=color, linewidth=linewidth)
 
         # ## Non-iterable
         except TypeError:
             # ## DrawToolShape
-            if isinstance(geometry, DrawToolShape):
-                plot_elements += self.plot_shape(geometry=geometry.geo, color=color, linewidth=linewidth)
+            if isinstance(use_geometry, DrawToolShape):
+                plot_elements += self.plot_shape(geometry=use_geometry.geo, color=color, linewidth=linewidth)
 
             # ## Polygon: Descend into exterior and each interior.
-            if isinstance(geometry, Polygon):
-                plot_elements += self.plot_shape(geometry=geometry.exterior, color=color, linewidth=linewidth)
-                plot_elements += self.plot_shape(geometry=geometry.interiors, color=color, linewidth=linewidth)
+            if isinstance(use_geometry, Polygon):
+                plot_elements += self.plot_shape(geometry=use_geometry.exterior, color=color, linewidth=linewidth)
+                plot_elements += self.plot_shape(geometry=use_geometry.interiors, color=color, linewidth=linewidth)
 
-            if isinstance(geometry, (LineString, LinearRing)):
-                plot_elements.append(self.shapes.add(shape=geometry, color=color, layer=0, tolerance=self.tolerance))
+            if isinstance(use_geometry, (LineString, LinearRing)):
+                plot_elements.append(self.shapes.add(shape=use_geometry, color=color, layer=0,
+                                                     tolerance=self.tolerance))
 
             if type(geometry) == Point:
                 pass
@@ -3837,6 +3852,7 @@ class AppExcEditor(QtCore.QObject):
         if val == 'linear':
             self.ui.array_circular_frame.hide()
             self.ui.array_linear_frame.show()
+            self.app.inform.emit(_("Click to place ..."))
         else:
             self.delete_utility_geometry()
             self.ui.array_circular_frame.show()
@@ -3847,6 +3863,7 @@ class AppExcEditor(QtCore.QObject):
         if val == 'linear':
             self.ui.slot_array_circular_frame.hide()
             self.ui.slot_array_linear_frame.show()
+            self.app.inform.emit(_("Click to place ..."))
         else:
             self.delete_utility_geometry()
             self.ui.slot_array_circular_frame.show()
diff --git a/appEditors/AppGeoEditor.py b/appEditors/AppGeoEditor.py
index 151c6a1c..c9d6c2b3 100644
--- a/appEditors/AppGeoEditor.py
+++ b/appEditors/AppGeoEditor.py
@@ -1697,31 +1697,35 @@ class DrawToolShape(object):
 
         # Iterable: descend into each item.
         try:
-            for subo in o:
-                pts += DrawToolShape.get_pts(subo)
+            if isinstance(o, (MultiPolygon,  MultiLineString)):
+                for subo in o.geoms:
+                    pts += DrawToolShape.get_pts(subo)
+            else:
+                for subo in o:
+                    pts += DrawToolShape.get_pts(subo)
         # Non-iterable
         except TypeError:
-            if o is not None:
-                # DrawToolShape: descend into .geo.
-                if isinstance(o, DrawToolShape):
-                    pts += DrawToolShape.get_pts(o.geo)
-
-                # Descend into .exterior and .interiors
-                elif type(o) == Polygon:
-                    pts += DrawToolShape.get_pts(o.exterior)
-                    for i in o.interiors:
-                        pts += DrawToolShape.get_pts(i)
-                elif type(o) == MultiLineString:
-                    for line in o:
-                        pts += DrawToolShape.get_pts(line)
-                # Has .coords: list them.
-                else:
-                    if DrawToolShape.tolerance is not None:
-                        pts += list(o.simplify(DrawToolShape.tolerance).coords)
-                    else:
-                        pts += list(o.coords)
-            else:
+            if o is  None:
                 return
+
+            # DrawToolShape: descend into .geo.
+            if isinstance(o, DrawToolShape):
+                pts += DrawToolShape.get_pts(o.geo)
+
+            # Descend into .exterior and .interiors
+            elif isinstance(o, Polygon):
+                pts += DrawToolShape.get_pts(o.exterior)
+                for i in o.interiors:
+                    pts += DrawToolShape.get_pts(i)
+            elif isinstance(o, (MultiLineString, MultiPolygon)):
+                for geo_pol_line in o.geoms:
+                    pts += DrawToolShape.get_pts(geo_pol_line)
+            # Has .coords: list them.
+            else:
+                if DrawToolShape.tolerance is not None:
+                    pts += list(o.simplify(DrawToolShape.tolerance).coords)
+                else:
+                    pts += list(o.coords)
         return pts
 
     def __init__(self, geo: (BaseGeometry, list)):
diff --git a/appGUI/VisPyVisuals.py b/appGUI/VisPyVisuals.py
index 38d6854b..23d4ebee 100644
--- a/appGUI/VisPyVisuals.py
+++ b/appGUI/VisPyVisuals.py
@@ -335,6 +335,7 @@ class ShapeCollectionVisual(CompoundVisual):
         :param update: bool
             Set True to redraw collection
         """
+        self.last_key = -1
         self.data.clear()
         if update:
             self.__update()
diff --git a/appGUI/preferences/PreferencesUIManager.py b/appGUI/preferences/PreferencesUIManager.py
index 67d81fbc..f994413a 100644
--- a/appGUI/preferences/PreferencesUIManager.py
+++ b/appGUI/preferences/PreferencesUIManager.py
@@ -33,6 +33,8 @@ class PreferencesUIManager:
         self.inform = inform
         self.ignore_tab_close_event = False
 
+        self.preferences_units = "MM"
+
         # if Preferences are changed in the Edit -> Preferences tab the value will be set to True
         self.preferences_changed_flag = False
 
@@ -1114,14 +1116,8 @@ class PreferencesUIManager:
         # restore stylesheet to default for the statusBar icon
         self.ui.pref_status_label.setStyleSheet("")
 
-        try:
-            self.ui.general_pref_form.general_app_group.units_radio.activated_custom.disconnect()
-        except (TypeError, AttributeError):
-            pass
-
         self.defaults_write_form(source_dict=self.defaults.current_defaults)
-        self.ui.general_pref_form.general_app_group.units_radio.activated_custom.connect(
-            lambda: self.ui.app.on_toggle_units(no_pref=False))
+
         self.defaults.update(self.defaults.current_defaults)
 
         # Preferences save, update the color of the Preferences Tab text
@@ -1144,6 +1140,7 @@ class PreferencesUIManager:
         self.defaults.reset_to_factory_defaults()
         self.defaults_write_form()
         self.on_preferences_edited()
+        self.ui.units_label.setText("[mm]")
         self.inform.emit('[success] %s' % _("Preferences default values are restored."))
 
     def save_defaults(self, silent=False, data_path=None, first_time=False):
diff --git a/appObjects/FlatCAMDocument.py b/appObjects/FlatCAMDocument.py
index 01bcd80b..c8af83a3 100644
--- a/appObjects/FlatCAMDocument.py
+++ b/appObjects/FlatCAMDocument.py
@@ -9,6 +9,7 @@
 # ##########################################################
 # File modified by: Marius Stanciu                         #
 # ##########################################################
+from PyQt6 import QtGui
 
 from appEditors.AppTextEditor import AppTextEditor
 from appObjects.FlatCAMObj import *
diff --git a/appObjects/FlatCAMGerber.py b/appObjects/FlatCAMGerber.py
index 50344572..32a48bbf 100644
--- a/appObjects/FlatCAMGerber.py
+++ b/appObjects/FlatCAMGerber.py
@@ -943,7 +943,7 @@ class GerberObject(FlatCAMObj, Gerber):
 
             plot_geometry = geometry.geoms if isinstance(geometry, (MultiPolygon, MultiLineString)) else geometry
             for g in plot_geometry:
-                if isinstance(g, (Polygon, LineString)):
+                if isinstance(g, (Polygon, LineString, LinearRing)):
                     self.add_shape(shape=g, color=used_color, face_color=used_face_color, visible=visible)
 
             self.shapes.redraw(
diff --git a/appParsers/ParseGerber.py b/appParsers/ParseGerber.py
index 6afefb1c..a36c6e68 100644
--- a/appParsers/ParseGerber.py
+++ b/appParsers/ParseGerber.py
@@ -1701,11 +1701,15 @@ class Gerber(Geometry):
                 # features
                 if self.app.defaults['gerber_extra_buffering']:
                     candidate_geo = []
+                    if isinstance(self.solid_geometry, MultiPolygon):
+                        geo_to_buff = self.solid_geometry.geoms
+                    else:
+                        geo_to_buff = self.solid_geometry
                     try:
-                        for p in self.solid_geometry:
+                        for p in geo_to_buff:
                             candidate_geo.append(p.buffer(-0.0000001))
                     except TypeError:
-                        candidate_geo.append(self.solid_geometry.buffer(-0.0000001))
+                        candidate_geo.append(geo_to_buff.buffer(-0.0000001))
                     self.solid_geometry = candidate_geo
 
             else:
@@ -2106,7 +2110,10 @@ class Gerber(Geometry):
         # variables to display the percentage of work done
         self.geo_len = 0
         try:
-            self.geo_len = len(self.solid_geometry)
+            if isinstance(self.solid_geometry, MultiPolygon):
+                self.geo_len = len(self.solid_geometry.geoms)
+            else:
+                self.geo_len = len(self.solid_geometry)
         except TypeError:
             self.geo_len = 1
 
diff --git a/app_Main.py b/app_Main.py
index 61e2e026..c276ae4a 100644
--- a/app_Main.py
+++ b/app_Main.py
@@ -1436,9 +1436,6 @@ class App(QtCore.QObject):
         # #################################### GUI PREFERENCES SIGNALS ##############################################
         # ###########################################################################################################
 
-        self.ui.general_pref_form.general_app_group.units_radio.activated_custom.connect(
-            lambda: self.on_toggle_units(no_pref=False))
-
         # ##################################### Workspace Setting Signals ###########################################
         self.ui.general_pref_form.general_app_set_group.wk_cb.currentIndexChanged.connect(
             self.on_workspace_modified)
@@ -4590,99 +4587,23 @@ class App(QtCore.QObject):
         self.ui.units_label.setText("[" + units.lower() + "]")
 
     def on_toggle_units_click(self):
-        try:
-            self.ui.general_pref_form.general_app_group.units_radio.activated_custom.disconnect()
-        except (TypeError, AttributeError):
-            pass
+        new_units, factor =  self.on_toggle_units()
+        if self.ui.plot_tab_area.currentWidget().objectName() == "preferences_tab":
+            if factor != 1:     # means we had a unit change in the rest of the app
+                pref_units = self.preferencesUiManager.preferences_units
+                if pref_units != new_units:
+                    self.preferencesUiManager.preferences_units = new_units
+                    pref_factor = 25.4 if new_units == 'MM' else 1 / 25.4
+                    self.scale_preferenes(pref_factor, new_units)
 
-        if self.defaults["units"] == 'MM':
-            self.ui.general_pref_form.general_app_group.units_radio.set_value("IN")
-        else:
-            self.ui.general_pref_form.general_app_group.units_radio.set_value("MM")
+                    # update th new units in the preferences storage
+                    self.defaults["units"] = new_units
 
-        self.on_toggle_units(no_pref=True)
+    def scale_preferenes(self, sfactor, new_units):
+        self.preferencesUiManager.defaults_read_form()
 
-        self.ui.general_pref_form.general_app_group.units_radio.activated_custom.connect(
-            lambda: self.on_toggle_units(no_pref=False))
-
-    def scale_defaults(self, sfactor, dimensions):
-        for dim in dimensions:
-            if dim in ['tools_mill_tooldia', 'tools_ncc_tools', 'tools_solderpaste_tools', 'tools_iso_tooldia',
-                       'tools_paint_tooldia', 'tools_transform_ref_point', 'tools_cal_toolchange_xy',
-                       'gerber_editor_newdim', 'tools_drill_toolchangexy', 'tools_drill_endxy',
-                       'tools_mill_toolchangexy', 'tools_mill_endxy', 'tools_solderpaste_xy_toolchange']:
-                if not self.defaults[dim] or self.defaults[dim] == '':
-                    continue
-
-                if isinstance(self.defaults[dim], str):
-                    try:
-                        tools_diameters = eval(self.defaults[dim])
-                    except Exception as e:
-                        self.log.error("App.on_toggle_units().scale_defaults() lists --> %s" % str(e))
-                        continue
-                elif isinstance(self.defaults[dim], (float, int)):
-                    tools_diameters = [self.defaults[dim]]
-                else:
-                    tools_diameters = list(self.defaults[dim])
-
-                if isinstance(tools_diameters, (tuple, list)):
-                    pass
-                elif isinstance(tools_diameters, (int, float)):
-                    tools_diameters = [self.defaults[dim]]
-                else:
-                    continue
-
-                td_len = len(tools_diameters)
-                conv_list = []
-                for t in range(td_len):
-                    conv_list.append(self.dec_format(float(tools_diameters[t]) * sfactor, self.decimals))
-
-                self.defaults[dim] = conv_list
-            elif dim in ['global_gridx', 'global_gridy']:
-                # format the number of decimals to the one specified in self.decimals
-                try:
-                    val = float(self.defaults[dim]) * sfactor
-                except Exception as e:
-                    self.log.error('App.on_toggle_units().scale_defaults() grids --> %s' % str(e))
-                    continue
-
-                self.defaults[dim] = self.dec_format(val, self.decimals)
-            else:
-                # the number of decimals for the rest is kept unchanged
-                if self.defaults[dim]:
-                    try:
-                        val = float(self.defaults[dim]) * sfactor
-                    except Exception as e:
-                        self.log.error(
-                            'App.on_toggle_units().scale_defaults() standard --> Value: %s %s' % (str(dim), str(e))
-                        )
-                        continue
-
-                    self.defaults[dim] = self.dec_format(val, self.decimals)
-
-    def on_toggle_units(self, no_pref=False):
-        """
-        Callback for the Units radio-button change in the Preferences tab.
-        Changes the application's default units adn for the project too.
-        If changing the project's units, the change propagates to all of
-        the objects in the project.
-
-        :return: None
-        """
-
-        self.defaults.report_usage("on_toggle_units")
-
-        if self.toggle_units_ignore:
-            return
-
-        new_units = self.ui.general_pref_form.general_app_group.units_radio.get_value().upper()
-
-        # If option is the same, then ignore
-        if new_units == self.defaults["units"].upper():
-            self.log.debug("on_toggle_units(): Same as previous, ignoring.")
-            return
-
-        # new_units = self.defaults["units"]
+        # update the defaults from form, some may assume that the conversion is enough and it's not
+        self.on_options_app2project()
 
         # Keys in self.defaults for which to scale their values
         dimensions = [
@@ -4723,7 +4644,7 @@ class App(QtCore.QObject):
             'tools_drill_endxy', 'tools_drill_feedrate_z', 'tools_drill_toolchangez', "tools_drill_drill_overlap",
             'tools_drill_offset', "tools_drill_toolchangexy", "tools_drill_startz", 'tools_drill_feedrate_rapid',
             "tools_drill_feedrate_probe", "tools_drill_z_pdepth", "tools_drill_area_overz",
-            
+
             # NCC Tool
             "tools_ncc_tools", "tools_ncc_margin", "tools_ncc_offset_value", "tools_ncc_cutz", "tools_ncc_tipdia",
             "tools_ncc_newdia",
@@ -4794,11 +4715,86 @@ class App(QtCore.QObject):
             "tools_invert_margin",
 
         ]
+        for dim in dimensions:
+            if dim in ['tools_mill_tooldia', 'tools_ncc_tools', 'tools_solderpaste_tools', 'tools_iso_tooldia',
+                       'tools_paint_tooldia', 'tools_transform_ref_point', 'tools_cal_toolchange_xy',
+                       'gerber_editor_newdim', 'tools_drill_toolchangexy', 'tools_drill_endxy',
+                       'tools_mill_toolchangexy', 'tools_mill_endxy', 'tools_solderpaste_xy_toolchange']:
+                if not self.defaults[dim] or self.defaults[dim] == '':
+                    continue
 
-        # The scaling factor depending on choice of units.
-        factor = 25.4 if new_units == 'MM' else 1 / 25.4
+                if isinstance(self.defaults[dim], str):
+                    try:
+                        tools_diameters = eval(self.defaults[dim])
+                    except Exception as e:
+                        self.log.error("App.on_toggle_units().scale_defaults() lists --> %s" % str(e))
+                        continue
+                elif isinstance(self.defaults[dim], (float, int)):
+                    tools_diameters = [self.defaults[dim]]
+                else:
+                    tools_diameters = list(self.defaults[dim])
 
-        # Changing project units. Warn user.
+                if isinstance(tools_diameters, (tuple, list)):
+                    pass
+                elif isinstance(tools_diameters, (int, float)):
+                    tools_diameters = [self.defaults[dim]]
+                else:
+                    continue
+
+                td_len = len(tools_diameters)
+                conv_list = []
+                for t in range(td_len):
+                    conv_list.append(self.dec_format(float(tools_diameters[t]) * sfactor, self.decimals))
+
+                self.defaults[dim] = conv_list
+            elif dim in ['global_gridx', 'global_gridy']:
+                # format the number of decimals to the one specified in self.decimals
+                try:
+                    val = float(self.defaults[dim]) * sfactor
+                except Exception as e:
+                    self.log.error('App.on_toggle_units().scale_defaults() grids --> %s' % str(e))
+                    continue
+
+                self.defaults[dim] = self.dec_format(val, self.decimals)
+            else:
+                # the number of decimals for the rest is kept unchanged
+                if self.defaults[dim]:
+                    try:
+                        val = float(self.defaults[dim]) * sfactor
+                    except Exception as e:
+                        self.log.error(
+                            'App.on_toggle_units().scale_defaults() standard --> Value: %s %s' % (str(dim), str(e))
+                        )
+                        continue
+
+                    self.defaults[dim] = self.dec_format(val, self.decimals)
+
+        self.preferencesUiManager.defaults_write_form(fl_units=new_units)
+
+    def on_toggle_units(self):
+        """
+        Callback for the Units radio-button change in the Preferences tab.
+        Changes the application's default units adn for the project too.
+        If changing the project's units, the change propagates to all of
+        the objects in the project.
+
+        :return: The new application units. String: "IN" or "MM" with caps lock
+        """
+
+        if self.toggle_units_ignore:
+            return
+
+        new_units = self.defaults["units"]
+
+        # we can't change the units while inside the Editors
+        if self.call_source in ['geo_editor', 'grb_editor', 'exc_editor']:
+            msg = _("Units cannot be changed while the editor is active.")
+            self.inform.emit("[WARNING_NOTCL] %s" % msg)
+            return
+
+        # ##############################################################################################################
+        # Changing project units. Ask the user.
+        # ##############################################################################################################
         msgbox = QtWidgets.QMessageBox()
         msgbox.setWindowTitle(_("Toggle Units"))
         msgbox.setWindowIcon(QtGui.QIcon(self.resource_location + '/toggle_units32.png'))
@@ -4815,26 +4811,21 @@ class App(QtCore.QObject):
         response = msgbox.clickedButton()
 
         if response == bt_ok:
-            if no_pref is False:
-                self.preferencesUiManager.defaults_read_form()
-                self.scale_defaults(factor, dimensions)
-                self.preferencesUiManager.defaults_write_form(fl_units=new_units)
+            new_units = "IN" if self.defaults['units'].upper() == "MM" else "MM"
 
-                self.defaults["units"] = new_units
+            # The scaling factor depending on choice of units.
+            factor = 25.4 if new_units == 'MM' else 1 / 25.4
 
-                # update the defaults from form, some may assume that the conversion is enough and it's not
-                self.on_options_app2project()
-
-            # update the objects
+            # update the Application objects with the new units
             for obj in self.collection.get_list():
                 obj.convert_units(new_units)
-
                 # make that the properties stored in the object are also updated
                 self.app_obj.object_changed.emit(obj)
+
                 # rebuild the object UI
                 obj.build_ui()
 
-            # change this only if the workspace is active
+            # update workspace if active
             if self.defaults['global_workspace'] is True:
                 self.plotcanvas.draw_workspace(pagesize=self.defaults['global_workspaceT'])
 
@@ -4842,30 +4833,23 @@ class App(QtCore.QObject):
             val_x = float(self.defaults['global_gridx']) * factor
             val_y = val_x if self.ui.grid_gap_link_cb.isChecked() else float(self.defaults['global_gridx']) * factor
 
+            # update Object UI forms
             current = self.collection.get_active()
             if current is not None:
                 # the transfer of converted values to the UI form for Geometry is done local in the FlatCAMObj.py
                 if not isinstance(current, GeometryObject):
                     current.to_form()
 
-            # replot all objects
+            # plot again all objects
             self.plot_all()
-
-            # set the status labels to reflect the current FlatCAM units
             self.set_screen_units(new_units)
 
-            # signal to the app that we changed the object properties and it should save the project
+            # flag for the app that we changed the object properties and it should save the project
             self.should_we_save = True
 
             self.inform.emit('[success] %s: %s' % (_("Converted units to"), new_units))
         else:
-            # Undo toggling
-            self.toggle_units_ignore = True
-            if self.defaults['units'].upper() == 'MM':
-                self.ui.general_pref_form.general_app_group.units_radio.set_value('IN')
-            else:
-                self.ui.general_pref_form.general_app_group.units_radio.set_value('MM')
-            self.toggle_units_ignore = False
+            factor = 1
 
             # store the grid values so they are not changed in the next step
             val_x = float(self.defaults['global_gridx'])
@@ -4875,14 +4859,14 @@ class App(QtCore.QObject):
 
         self.preferencesUiManager.defaults_read_form()
 
-        # the self.preferencesUiManager.defaults_read_form() will update all defaults values
-        # in self.defaults from the GUI elements but
-        # I don't want it for the grid values, so I update them here
+        # update the Grid snap values
         self.defaults['global_gridx'] = val_x
         self.defaults['global_gridy'] = val_y
         self.ui.grid_gap_x_entry.set_value(val_x, decimals=self.decimals)
         self.ui.grid_gap_y_entry.set_value(val_y, decimals=self.decimals)
 
+        return new_units, factor
+
     def on_deselect_all(self):
         self.collection.set_all_inactive()
         self.delete_selection_shape()
@@ -5615,17 +5599,8 @@ class App(QtCore.QObject):
         # Set the relative position label
         dx = location[0] - float(self.rel_point1[0])
         dy = location[1] - float(self.rel_point1[1])
-        # self.ui.position_label.setText("&nbsp;<b>X</b>: %.4f&nbsp;&nbsp;   "
-        #                                "<b>Y</b>: %.4f&nbsp;" % (location[0], location[1]))
-        # # Set the position label
-        # self.ui.rel_position_label.setText("<b>Dx</b>: %.4f&nbsp;&nbsp;  <b>Dy</b>: "
-        #                                    "%.4f&nbsp;&nbsp;&nbsp;&nbsp;" % (dx, dy))
-        self.ui.update_location_labels(dx, dy, location[0], location[1])
 
-        # units = self.defaults["units"].lower()
-        # self.plotcanvas.text_hud.text = \
-        #     'Dx:\t{:<.4f} [{:s}]\nDy:\t{:<.4f} [{:s}]\n\nX:  \t{:<.4f} [{:s}]\nY:  \t{:<.4f} [{:s}]'.format(
-        #         dx, units, dy, units, location[0], units, location[1], units)
+        self.ui.update_location_labels(dx, dy, location[0], location[1])
         self.plotcanvas.on_update_text_hud(dx, dy, location[0], location[1])
 
         self.inform.emit('[success] %s' % _("Done."))
diff --git a/defaults.py b/defaults.py
index adc4f72a..85674c4d 100644
--- a/defaults.py
+++ b/defaults.py
@@ -24,6 +24,7 @@ class FlatCAMDefaults:
 
     factory_defaults = {
         # Global
+        "units": "MM",
         "version": 8.992,  # defaults format version, not necessarily equal to app version
         "first_run": True,
         "root_folder_path": '',
@@ -78,7 +79,6 @@ class FlatCAMDefaults:
         "global_tcl_path": '',
 
         # General APP Preferences
-        "units": "MM",
         "decimals_inch": 4,
         "decimals_metric": 4,
         "global_graphic_engine": '3D',