[FIX] web: improve automatic creation of new lines in x2many in forms

This commit fixes a few issues with the previous implementation of the
automatic addition of new lines in x2many inside forms

1. Before this commit, when there is a change of mode in a formview
`edit` -> `readonly` -> `edit`, there may be some cases that
mistakenly and automatically opens a modal.

This case occurs in a form view with a x2many field whose 1st inner
focusable element opens a modal (e.g. "Add an item").

In `edit` mode:
	1. Open this modal from the x2many
	2. Close the modal
	3. Change mode to `readonly`
	4. Change mode to `edit`
> the same modal is automatically open.

This is due to the tracking of the last activated field that persists
after a change of mode. Since the last activated field in the 1st
`edit` is the x2many, it is granted the focus at the beginning of the
2nd `edit`, which automatically opens the modal.

This commit fixes the issue by resetting the tracking of the last
activated field when there is a change of mode. As a result, at the
beginning of the 2nd `edit`, the focus should always be on the 1st
field.

2. Before this commit, if the focus was moved out of the form (to a modal
for instance) then back, the form would re-activate the last field, which
is the x2many and would re-add a new line. This behavior is not correct
and now going back from a modal to a form does not add a new line.

Co-authored-by: Alexandre Kühn <aku@odoo.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/addons/web/static/src/js/fields/relational_fields.js b/addons/web/static/src/js/fields/relational_fields.js
index c3d25f37d09..7a428923608 100644
--- a/addons/web/static/src/js/fields/relational_fields.js
+++ b/addons/web/static/src/js/fields/relational_fields.js
@@ -906,8 +906,10 @@ var FieldX2Many = AbstractField.extend({
 
     /**
      * @override
+     * @param {Object|undefined} [options={}]
+     * @param {boolean} [options.noAutomaticCreate=false]
      */
-    activate: function () {
+    activate: function (options) {
         if (!this.activeActions.create || this.isReadonly || !this.$el.is(":visible")) {
             return false;
         }
@@ -915,7 +917,11 @@ var FieldX2Many = AbstractField.extend({
             this.$buttons.find(".o-kanban-button-new").focus();
         }
         if (this.view.arch.tag === 'tree') {
-            this.renderer.$('.o_field_x2many_list_row_add a:first').focus();
+            if (options && options.noAutomaticCreate) {
+                this.renderer.$('.o_field_x2many_list_row_add a:first').focus();
+            } else {
+                this.renderer.$('.o_field_x2many_list_row_add a:first').click();
+            }
         }
         return true;
     },