gtk/columnview: Invert resizing drag direction in RTL

Reverse the side of column resizing drag handle in RTL and change
the base for drag coordinates and the column resizing caluculations.

Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/6049

gtk/gtkcolumnview.c

@@ -484,7 +484,7 @@ gtk_column_view_allocate (GtkWidget *widget,
                           int        baseline)
 {
   GtkColumnView *self = GTK_COLUMN_VIEW (widget);
-  int full_width, header_height, min, nat, x;
+  int full_width, header_height, min, nat, x, dx;
 
   x = gtk_adjustment_get_value (self->hadjustment);
   full_width = gtk_column_view_allocate_columns (self, width);
@@ -494,12 +494,15 @@ gtk_column_view_allocate (GtkWidget *widget,
     header_height = min;
   else
     header_height = nat;
+
+  dx = (_gtk_widget_get_direction (widget) != GTK_TEXT_DIR_RTL) ? -x : width - full_width + x;
+
   gtk_widget_allocate (self->header, full_width, header_height, -1,
-                       gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (-x, 0)));
+                       gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (dx, 0)));
 
   gtk_widget_allocate (GTK_WIDGET (self->listview),
                        full_width, height - header_height, -1,
-                       gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (-x, header_height)));
+                       gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (dx, header_height)));
 
   gtk_adjustment_configure (self->hadjustment,  x, 0, full_width, width * 0.1, width * 0.9, width);
 }
@@ -1065,7 +1068,9 @@ gtk_column_view_in_resize_rect (GtkColumnView       *self,
   gtk_column_view_column_get_allocation (column, NULL, &width);
   rect.size.width = width;
 
-  rect.origin.x += rect.size.width - DRAG_WIDTH / 2;
+  if (_gtk_widget_get_direction (GTK_WIDGET (self)) != GTK_TEXT_DIR_RTL)
+    rect.origin.x += rect.size.width;
+  rect.origin.x -= DRAG_WIDTH / 2;
   rect.size.width = DRAG_WIDTH;
 
   return graphene_rect_contains_point (&rect, &(graphene_point_t) { x, y});
@@ -1142,7 +1147,14 @@ header_drag_begin (GtkGestureDrag *gesture,
           gtk_column_view_column_set_fixed_width (column, size);
 
           self->drag_pos = i;
-          self->drag_x = start_x - size;
+          if (_gtk_widget_get_direction (GTK_WIDGET (self)) != GTK_TEXT_DIR_RTL)
+            self->drag_x = start_x - size;
+          else
+            {
+              int width = gtk_widget_get_width (GTK_WIDGET (self->header));
+
+              self->drag_x = width - (start_x + size);
+            }
           self->in_column_resize = TRUE;
 
           set_resize_cursor (self, TRUE);
@@ -1254,6 +1266,13 @@ update_column_resize (GtkColumnView *self,
 {
   GtkColumnViewColumn *column;
 
+  if (_gtk_widget_get_direction (GTK_WIDGET (self)) == GTK_TEXT_DIR_RTL)
+    {
+      int width = gtk_widget_get_width (GTK_WIDGET (self->header));
+
+      x = width - x;
+    }
+
   column = g_list_model_get_item (G_LIST_MODEL (self->columns), self->drag_pos);
   gtk_column_view_column_set_fixed_width (column, MAX (x - self->drag_x, 0));
   g_object_unref (column);

gtk/gtkrange.c

@@ -2291,9 +2291,9 @@ update_autoscroll_mode (GtkRange *range,
         }
 
       if (pos < SCROLL_EDGE_SIZE)
-        mode = priv->inverted ? GTK_SCROLL_STEP_FORWARD : GTK_SCROLL_STEP_BACKWARD;
+        mode = should_invert (range) ? GTK_SCROLL_STEP_FORWARD : GTK_SCROLL_STEP_BACKWARD;
       else if (pos > (size - SCROLL_EDGE_SIZE))
-        mode = priv->inverted ? GTK_SCROLL_STEP_BACKWARD : GTK_SCROLL_STEP_FORWARD;
+        mode = should_invert (range) ? GTK_SCROLL_STEP_BACKWARD : GTK_SCROLL_STEP_FORWARD;
     }
 
   if (mode != priv->autoscroll_mode)

gtk/gtkscrollbar.c

@@ -263,6 +263,7 @@ gtk_scrollbar_init (GtkScrollbar *self)
   priv->orientation = GTK_ORIENTATION_HORIZONTAL;
 
   priv->range = g_object_new (GTK_TYPE_RANGE, NULL);
+  gtk_range_set_flippable (GTK_RANGE (priv->range), TRUE);
   gtk_widget_set_hexpand (priv->range, TRUE);
   gtk_widget_set_vexpand (priv->range, TRUE);
   gtk_widget_set_parent (priv->range, GTK_WIDGET (self));