patch 8.2.1228: scrollbars not flush against the window edges when maximised

Problem:    Scrollbars not flush against the window edges when maximised.
Solution:   Add padding. (Ken Takata, closes #5602, closes #6466)
diff --git a/src/gui_athena.c b/src/gui_athena.c
index 6a64de5..4384740 100644
--- a/src/gui_athena.c
+++ b/src/gui_athena.c
@@ -1889,6 +1889,22 @@
     XtManageChild(sb->id);
 }
 
+    int
+gui_mch_get_scrollbar_xpadding(void)
+{
+    // TODO: Calculate the padding for adjust scrollbar position when the
+    // Window is maximized.
+    return 0;
+}
+
+    int
+gui_mch_get_scrollbar_ypadding(void)
+{
+    // TODO: Calculate the padding for adjust scrollbar position when the
+    // Window is maximized.
+    return 0;
+}
+
     void
 gui_mch_enable_scrollbar(scrollbar_T *sb, int flag)
 {