#5366, #5975 - Fixes open rightward/leftward incorrectly adjusting to scroll context

src/definitions/modules/dropdown.js

@@ -3259,6 +3259,7 @@ $.fn.dropdown = function(parameters) {
             ;
             calculations = {
               context: {
+                offset     : $context.offset(),
                 scrollLeft : $context.scrollLeft(),
                 width      : $context.outerWidth()
               },
@@ -3270,7 +3271,7 @@ $.fn.dropdown = function(parameters) {
             if(module.is.horizontallyScrollableContext()) {
               calculations.menu.offset.left += calculations.context.scrollLeft;
             }
-            isOffscreenRight = (calculations.menu.offset.left + calculations.menu.width >= calculations.context.scrollLeft + calculations.context.width);
+            isOffscreenRight = (calculations.menu.offset.left - calculations.context.offset.left + calculations.menu.width >= calculations.context.scrollLeft + calculations.context.width);
             if(isOffscreenRight) {
               module.verbose('Dropdown cannot fit in context rightward', isOffscreenRight);
               canOpenRightward = false;