MDL-47353 gradereport_grader: Fix header offset logic for floating headers

This is necessary for themes with non-fixed navbars to work with the
grader report, otherwise headers will be hidden.

This issue is a part of the MDL-46658 Task.
This issue is a part of the MDL-25544 Epic.

grade/report/grader/yui/build/moodle-gradereport_grader-gradereporttable/moodle-gradereport_grader-gradereporttable-debug.js

@@ -485,6 +485,13 @@ FloatingHeaders.prototype = {
         if (header) {
             if (header.getComputedStyle('position') === 'fixed') {
                 this.pageHeaderHeight = header.get(OFFSETHEIGHT);
+            } else {
+                var navbar = Y.one('.navbar');
+
+                if (navbar) {
+                    // If the navbar exists and isn't fixed, we need to offset the page header to accommodate for it.
+                    this.pageHeaderHeight = navbar.get(OFFSETHEIGHT);
+                }
             }
         }
     },

grade/report/grader/yui/build/moodle-gradereport_grader-gradereporttable/moodle-gradereport_grader-gradereporttable.js

@@ -485,6 +485,13 @@ FloatingHeaders.prototype = {
         if (header) {
             if (header.getComputedStyle('position') === 'fixed') {
                 this.pageHeaderHeight = header.get(OFFSETHEIGHT);
+            } else {
+                var navbar = Y.one('.navbar');
+
+                if (navbar) {
+                    // If the navbar exists and isn't fixed, we need to offset the page header to accommodate for it.
+                    this.pageHeaderHeight = navbar.get(OFFSETHEIGHT);
+                }
             }
         }
     },

grade/report/grader/yui/src/gradereporttable/js/floatingheaders.js

@@ -342,6 +342,13 @@ FloatingHeaders.prototype = {
         if (header) {
             if (header.getComputedStyle('position') === 'fixed') {
                 this.pageHeaderHeight = header.get(OFFSETHEIGHT);
+            } else {
+                var navbar = Y.one('.navbar');
+
+                if (navbar) {
+                    // If the navbar exists and isn't fixed, we need to offset the page header to accommodate for it.
+                    this.pageHeaderHeight = navbar.get(OFFSETHEIGHT);
+                }
             }
         }
     },

theme/upgrade.txt

@@ -11,7 +11,7 @@ information provided here is intended especially for theme designer.
 * On calendar view screen the course selector and new event button have been swapped, custom CSS for .path-calendar might be affected.
 * The functions search_listing() and search_pagination() in the core_course_management_renderer class take the searched string
   as an extra parameter - see MDL-46902.
-
+* Themes with non-fixed headers must have the .navbar class in their navbar in order for floating headers in the grader report to work - see MDL-46658. 
 
 === 2.7 ===