(js) Show mail compose btn if msgs list is visible

NEWS

@@ -17,6 +17,7 @@ Bug fixes
  - [web] fixed page reload with external IMAP account (#4709)
  - [web] constrained absolute-positioned child elements of HTML mail parts
  - [web] fixed useless scrolling when deleting a message
+ - [web] don't hide compose button if messages list is visible
  - [core] allow super users to modify any event (#4216)
  - [core] correctly handle the full cert chain in S/MIME
  - [core] handle multidays events in freebusy data

UI/Templates/MailerUI/UIxMailFolderTemplate.wox

@@ -329,7 +329,7 @@
   <md-fab-speed-dial
       class="md-scale sg-fab-bottom-center"
       ng-if="::!mailbox.composeWindowEnabled()"
-      ng-show="!mailbox.selectedFolder.hasSelectedMessage() || isGtMedium"
+      ng-show="!mailbox.selectedFolder.hasSelectedMessage() || isGtExtraSmall"
       ng-cloak="ng-cloak"
       ng-class="{ 'sg-sidenav-close': leftIsClose, 'sg-center-close': mailbox.centerIsClose(centerIsClose) }"
       md-direction="up">
@@ -356,7 +356,7 @@
       class="md-fab md-accent sg-fab-bottom-center"
       var:aria-label="Write a new message"
       ng-if="::mailbox.composeWindowEnabled()"
-      ng-show="!mailbox.selectedFolder.hasSelectedMessage() || isGtMedium"
+      ng-show="!mailbox.selectedFolder.hasSelectedMessage() || isGtExtraSmall"
       ng-class="{ 'sg-sidenav-close': leftIsClose, 'sg-center-close': mailbox.centerIsClose(centerIsClose) }"
       ng-click="mailbox.newMessage($event)">
     <md-tooltip md-direction="left"><var:string label:value="Write a new message"/></md-tooltip>

UI/WebServerResources/js/Common/navController.js

@@ -30,6 +30,13 @@
         }, 24 * 3600 * 1000);
       }, window.currentDay.secondsBeforeTomorrow * 1000);
 
+      // Track the 600px window width threashold
+      $scope.$watch(function() {
+        return $mdMedia(sgConstant['gt-xs']);
+      }, function(newVal) {
+        $scope.isGtExtraSmall = newVal;
+      });
+
       // Track the 1024px window width threashold
       $scope.$watch(function() {
         return $mdMedia(sgConstant['gt-md']);