[FIX] web,base: document template widget in settings

Go to General Settings, click on 'Change Document Template', and
in the opened dialog, click on a template.

Before this rev., it automatically closed the dialog, which was
not really convenient.

This rev. introduces a new field widget (image_selection) for
this use case, and ensures that the dialog doesn't close when
a template is selected.

Test written by @mba-odoo

addons/web/static/tests/fields/basic_fields_tests.js

@@ -38,6 +38,8 @@ QUnit.module('basic_fields', {
                     selection: {string: "Selection", type: "selection", searchable:true,
                         selection: [['normal', 'Normal'],['blocked', 'Blocked'],['done', 'Done']]},
                     document: {string: "Binary", type: "binary"},
+                    image_selection: {string: "Image Selection", type: "selection", searchable:true,
+                        selection: [['background', 'Background'],['boxed', 'Boxed'],['clean', 'Clean'],['standard', 'Standard']]},
                 },
                 records: [{
                     id: 1,
@@ -3995,6 +3997,45 @@ QUnit.module('basic_fields', {
 
         form.destroy();
     });
+
+    QUnit.module('FieldImageSelection');
+
+    QUnit.test('image selection widget in form view', function (assert) {
+        assert.expect(3);
+
+        var nodeOptions = {
+            background: {
+                image_link: '/base/static/img/preview_background.png',
+                preview_link: '/base/static/pdf/preview_background.pdf',
+            },
+            boxed: {
+                image_link: '/base/static/img/preview_boxed.png',
+                preview_link: '/base/static/pdf/preview_boxed.pdf',
+            },
+        };
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch: '<form>' +
+                    '<field name="image_selection" widget="image_selection"' +
+                    ' options=\'' + JSON.stringify(nodeOptions) + '\'/> '+
+                  '</form>',
+            res_id: 2,
+        });
+
+        assert.strictEqual(form.$('.img.img-responsive').length, 2,
+            "Two images should be rendered");
+        assert.strictEqual(form.$('.img.btn-info').length, 0,
+            "No image should be selected");
+
+        // select first image
+        form.$(".img.img-responsive:first").click();
+        assert.ok(form.$(".img.img-responsive:first").hasClass('btn-info'),
+            "First image should be selected");
+
+        form.destroy();
+    });
 });
 });
 });