adding input layer directly in table widget

bandtablewidgetbase.ui

@@ -15,6 +15,26 @@
   </property>
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="0">
+    <widget class="QLabel" name="label_2">
+     <property name="text">
+      <string>Raster layer</string>
+     </property>
+     <property name="buddy">
+      <cstring>cmbLayers</cstring>
+     </property>
+    </widget>
+   </item>
+   <item row="0" column="1">
+    <widget class="QgsMapLayerComboBox" name="cmbLayers">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+    </widget>
+   </item>
+   <item row="1" column="0" colspan="2">
     <widget class="QTreeWidget" name="bandClassTree">
      <column>
       <property name="text">
@@ -28,7 +48,7 @@
      </column>
     </widget>
    </item>
-   <item row="0" column="1">
+   <item row="1" column="3">
     <layout class="QVBoxLayout" name="verticalLayout">
      <item>
       <widget class="QToolButton" name="btnAdd">