title: Little blank space between toolbar and settings bar
body: <p>I have a strange issue that i cannot solve, i have a little spacing between my settings bar and the toolbar, <a href="https://i.stack.imgur.com/aZgXI.png" rel="nofollow noreferrer">watch here</a></p>
  
  <p><strong>my xml for the toolbar:</strong></p>
  
  <pre><code>&lt;android.support.v7.widget.Toolbar
      android:id="@+id/my_toolbar"
      android:layout_width="match_parent"
      android:layout_height="?attr/actionBarSize"
      android:background="?attr/colorPrimary"
      android:elevation="4dp"
      android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
      app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/&gt;
  </code></pre>
  
  <p><strong>on activity i call it like this:</strong></p>
  
  <p>Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
      setSupportActionBar(myToolbar);</p>
  
  <p>All Acitivity XML (put all my code in external file and include it)</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:fitsSystemWindows="true"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="com.example.afcosta.inesctec.pt.android.FamilyLibrary"
      android:paddingTop="6dp"&gt;
  
  
      &lt;android.support.design.widget.FloatingActionButton
          android:id="@+id/fab"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_gravity="bottom|end"
          android:layout_margin="@dimen/fab_margin"
          app:srcCompat="@android:drawable/ic_menu_camera"
          app:backgroundTint="#f1c40f"
          tools:layout_constraintRight_creator="1"
          tools:layout_constraintBottom_creator="1"
          app:layout_constraintBottom_toBottomOf="parent"
          android:layout_marginEnd="37dp"
          app:layout_constraintRight_toRightOf="parent"
          android:layout_marginBottom="33dp" /&gt;
  
      &lt;android.support.v7.widget.RecyclerView
          android:id="@+id/gallery"
          android:layout_width="0dp"
          android:layout_height="562dp"
          tools:layout_constraintTop_creator="1"
          tools:layout_constraintRight_creator="1"
          android:layout_marginStart="8dp"
          android:layout_marginEnd="8dp"
          app:layout_constraintRight_toRightOf="parent"
          android:layout_marginTop="97dp"
          tools:layout_constraintLeft_creator="1"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintTop_toTopOf="parent" /&gt;
  
      &lt;include
          layout="@layout/custom_toolbar"
          android:layout_height="wrap_content"
          android:layout_width="match_parent"
          android:id="@+id/toolbar"/&gt;
  
  
      &lt;TextView
          android:id="@+id/textView3"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Familias"
          android:textAppearance="@style/TextAppearance.AppCompat.Body1"
          tools:layout_constraintBottom_creator="1"
          app:layout_constraintBottom_toTopOf="@+id/gallery"
          android:layout_marginStart="8dp"
          tools:layout_constraintLeft_creator="1"
          android:layout_marginBottom="15dp"
          app:layout_constraintLeft_toLeftOf="parent"
          android:textSize="24dp"/&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>
  
  <p>it appears, but that strange white space is annoying :/</p>