Disable remove button of Many2Many if all selected records are already removed

sao/src/view/form.js

@@ -4083,10 +4083,17 @@ function eval_pyson(value){
                         (m2m_size >= field_size) && (field_size >= 0));
             }
 
+            var removable =
+                this.screen.selected_records.some((r) => !r.deleted && !r.removed);
+
             this.entry.prop('disabled', this._readonly || !record);
             this.but_add.prop('disabled', this._readonly || !record || size_limit);
             this.but_remove.prop(
-                'disabled', this._readonly || !record || this._position === 0);
+                'disabled',
+                this._readonly ||
+                !record ||
+                !removable ||
+                this._position === 0);
         },
         record_message: function(position, size) {
             this._position = position;

tryton/tryton/gui/window/view_form/view/form_gtk/many2many.py

@@ -284,11 +284,16 @@ class Many2Many(Widget):
         else:
             size_limit = False
 
+        removable = any(
+            not r.deleted and not r.removed
+            for r in self.screen.selected_records)
+
         self.but_add.set_sensitive(bool(
                 not self._readonly
                 and not size_limit))
         self.but_remove.set_sensitive(bool(
                 not self._readonly
+                and removable
                 and self._position))
 
     def record_message(self, position, size, *args):