FairEmail/app/src/main/res/layout/fragment_compose.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Spinner
        android:id="@+id/spFrom"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="6dp"
        android:layout_marginTop="6dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/ivIdentyAdd"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_marginStart="6dp"
        android:src="@drawable/baseline_person_add_24"
        app:layout_constraintStart_toEndOf="@id/spFrom"
        app:layout_constraintTop_toTopOf="@id/spFrom" />

    <EditText
        android:id="@+id/etTo"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="6dp"
        android:hint="@string/title_to"
        android:inputType="textEmailAddress"
        android:maxLines="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintEnd_toStartOf="@+id/ivContactAdd"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/spFrom" />

    <ImageView
        android:id="@+id/ivContactAdd"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_marginEnd="6dp"
        android:layout_marginStart="6dp"
        android:src="@drawable/baseline_person_24"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@id/etTo"
        app:layout_constraintTop_toTopOf="@+id/etTo" />

    <EditText
        android:id="@+id/etSubject"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="6dp"
        android:layout_marginStart="6dp"
        android:hint="@string/title_subject"
        android:inputType="textEmailSubject"
        android:maxLines="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etTo" />

    <View
        android:id="@+id/vSeparator"
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_marginTop="6dp"
        android:background="?attr/colorSeparator"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etSubject" />

    <ScrollView
        android:id="@+id/scroll"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_marginEnd="6dp"
        android:layout_marginStart="6dp"
        android:fillViewport="true"
        android:orientation="vertical"
        app:layout_constraintBottom_toTopOf="@+id/bottom_navigation"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/vSeparator">

        <EditText
            android:id="@+id/etBody"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@null"
            android:fontFamily="monospace"
            android:gravity="top"
            android:hint="@string/title_body_hint"
            android:inputType="textMultiLine"
            android:textAppearance="@style/TextAppearance.AppCompat.Small" />
    </ScrollView>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        app:itemIconTint="@color/colorActionForeground"
        app:itemTextColor="@color/colorActionForeground"
        app:labelVisibilityMode="unlabeled"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/action_compose" />

    <ProgressBar
        android:id="@+id/pbWait"
        style="@style/Base.Widget.AppCompat.ProgressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:indeterminate="true"
        app:layout_constraintBottom_toTopOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="parent" />

    <android.support.constraint.Group
        android:id="@+id/grpReady"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:constraint_referenced_ids="spFrom,ivIdentyAdd,etTo,etSubject,vSeparator,scroll,bottom_navigation" />
</android.support.constraint.ConstraintLayout>