add a mouse wheel delayer for EmtpyAreas

--add a mouse wheel delayer like in other Latte
MouseArea(s) in order to limit the actions
executed through mouse wheel in one second.
The user can now execute five actions at maximum
in one second.

containment/package/contents/ui/layouts/EnvironmentActions.qml

@@ -47,6 +47,8 @@ Loader {
             return useAllLayouts ? root.maxLength : root.realPanelLength;
         }
 
+        property bool wheelIsBlocked: false
+
         hoverEnabled: true
 
         readonly property bool useAllLayouts: panelUserSetAlignment === Latte.Types.Justify && !root.inConfigureAppletsMode
@@ -113,11 +115,18 @@ Loader {
         }
 
         onWheel: {
+            if (wheelIsBlocked) {
+                return;
+            }
+
             if (root.scrollAction === Latte.Types.ScrollNone) {
                 root.emptyAreasWheel(wheel);
                 return;
             }
 
+            wheelIsBlocked = true;
+            scrollDelayer.start();
+
             var delta = 0;
 
             if (wheel.angleDelta.y>=0 && wheel.angleDelta.x>=0) {
@@ -194,6 +203,17 @@ Loader {
             }
         }
 
+        //! A timer is needed in order to handle also touchpads that probably
+        //! send too many signals very fast. This way the signals per sec are limited.
+        //! The user needs to have a steady normal scroll in order to not
+        //! notice a annoying delay
+        Timer{
+            id: scrollDelayer
+
+            interval: 200
+            onTriggered: mainArea.wheelIsBlocked = false;
+        }
+
         //! Background Indicator
         Indicator.Bridge{
             id: indicatorBridge