Fixed tree menu positioning

Change-Id: I28cf53df1cfe60732da73af43adab998220c0f4a
diff --git a/dev/js/src/buttongroup/menu.js b/dev/js/src/buttongroup/menu.js
index 7ab149d..4615564 100644
--- a/dev/js/src/buttongroup/menu.js
+++ b/dev/js/src/buttongroup/menu.js
@@ -51,8 +51,10 @@
     // Attach menu to button
     button : function (btn) {
 
+      this._button = btn;
+
       // this._attached = e;
-      this._repos(btn);
+      this._repos(this._button);
       this.slider().reInit();
 
       /*
@@ -64,7 +66,7 @@
       };
 
       this._onscroll = function () {
-        this._repos(btn);
+        this._repos(this._button);
       }.bind(this);
       
       window.addEventListener('scroll', this._onscroll);
diff --git a/dev/js/src/match.js b/dev/js/src/match.js
index 3140de1..ad9a5b3 100644
--- a/dev/js/src/match.js
+++ b/dev/js/src/match.js
@@ -215,6 +215,7 @@
         loc.ADDTREE, ['tree'], function (e) {
           if (KorAP.TreeMenu === undefined) {
             KorAP.TreeMenu = buttonGroupMenuClass.create([], treeItemClass);
+            KorAP.TreeMenu.element().setAttribute('id', 'treeMenu');
           };
 
           var tm = KorAP.TreeMenu;
diff --git a/dev/scss/main/buttongroup.scss b/dev/scss/main/buttongroup.scss
index 0b89b11..269b5c1 100644
--- a/dev/scss/main/buttongroup.scss
+++ b/dev/scss/main/buttongroup.scss
@@ -77,9 +77,8 @@
 }
 
 
-ul.button-group-list {
+ul.menu.button-group-list {
   border-top-right-radius: 8px;
-  z-index: 150;
   font-size: 10pt;
   position: fixed;
   left: 0;