[FIX] mass_mailing: fix mobile preview

The preview of a mailing was displayed twice:
- after a save and when clicking on the preview button
- when double-clicking on the preview button
This solves those problems.

Technical notes: quick explanation of the fixes:
- double display after a save: the click event was registered twice (same for
the code preview button), the fix unregister the click before registering it
again.
- double display when double-clicking quickly on the button: the modal is not
displayed immediately and the button remains active a brief moment allowing a
second click. The fix disables the button when the button is clicked and
reenables it when the modal is closed.

Task-3047479

closes odoo/odoo#105974

X-original-commit: 0403938c3e0103d97ae828afdae06fcda06bd406
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/mass_mailing/static/src/js/mass_mailing_html_field.js

@@ -217,6 +217,8 @@ export class MassMailingHtmlField extends HtmlField {
             $snippetsSideBar.find('.o_codeview_btn').hide();
         }
         const $codeview = this.wysiwyg.$iframe.contents().find('textarea.o_codeview');
+        // Unbind first the event handler as this method can be called multiple time during the component life.
+        $snippetsSideBar.off('click', '.o_codeview_btn');
         $snippetsSideBar.on('click', '.o_codeview_btn', () => {
             this.wysiwyg.odooEditor.observerUnactive();
             $codeview.toggleClass('d-none');
@@ -230,8 +232,10 @@ export class MassMailingHtmlField extends HtmlField {
             }
             this.onIframeUpdated();
         });
-
-        $snippetsSideBar.on('click', '.o_mobile_preview_btn', () => {
+        const $previewBtn = $snippetsSideBar.find('.o_mobile_preview_btn');
+        $previewBtn.off('click');
+        $previewBtn.on('click', () => {
+            $previewBtn.prop('disabled', true); // Prevent double execution when double-clicking on the button
             let mailingHtml = new DOMParser().parseFromString(this.wysiwyg.getValue(), 'text/html');
             [...mailingHtml.querySelectorAll('a')].forEach(el => {
                 el.style.setProperty('pointer-events', 'none');
@@ -239,6 +243,8 @@ export class MassMailingHtmlField extends HtmlField {
             this.mobilePreview = this.dialog.add(MassMailingMobilePreviewDialog, {
                 title: this.env._t("Mobile Preview"),
                 preview: mailingHtml.body.innerHTML,
+            }, {
+                onClose: () => $previewBtn.prop('disabled', false),
             });
         });