Remove some css values, add variables for disabled dropdown #1615

RELEASE-NOTES.md

@@ -8,6 +8,7 @@
 
 **Enhancements**
 - **Grid** - Grid's ``equal height row` now uses a combination of `flexbox` and ``display: table-cell`` for older browsers
+- **Dropdown** - Dropdown can now be disabled by adding ``disabled` class without requiring `destroy`. **Thanks Psyton**
 - **Sidebar** - Having a sidebar visible on page load is now much simpler. You can include ``ui visible sidebar`` on page load to have a sidebar element appear on page load. To close call `$('.ui.sidebar').sidebar('hide')`
 - **Dropdown** - New `upward dropdown` variation, which opens its menu upward. Default animation now uses ``settings.transition = 'auto'` and determines direction of animation based on menu direction
 - **Dropdown** - Dropdown matching fields without values now trims whitespace by default

src/definitions/modules/dropdown.less

@@ -446,7 +446,7 @@ select.ui.dropdown {
   box-shadow: none;
   color: @selectionTextColor;
   border: @selectionBorder;
-  opacity: 0.3 !important;
+  opacity: @disabledOpacity !important;
 }
 
 /* Visible Hover */
@@ -693,6 +693,19 @@ select.ui.dropdown {
 }
 
 
+
+/*--------------------
+        Disabled
+----------------------*/
+
+/* Disabled */
+.ui.disabled.dropdown {
+  cursor: default;
+  pointer-events: none;
+  opacity: @disabledOpacity;
+}
+
+
 /*******************************
            Variations
 *******************************/