message: Make width of textboxes increase proportionally when resizing the Edit view (win)
diff: <RowDefinition Height="Auto"/>
  </Grid.RowDefinitions>
  <Grid.ColumnDefinitions>
  - <ColumnDefinition />
  + <ColumnDefinition Width="23*" />
  + <ColumnDefinition Width="16*"/>
  <ColumnDefinition Width="Auto"/>
  + <ColumnDefinition Width="16*" />
  </Grid.ColumnDefinitions>
  <TextBlock Style="{DynamicResource Toggl.BodyText}" Margin="0 0 0 8" Text="Duration" />
  <toggl:ExtendedTextBox x:Name="durationTextBox" x:FieldModifier="private" Grid.Row="1" Grid.Column="0"
  Style="{StaticResource {x:Type TextBox}}"
  LostKeyboardFocus="durationTextBox_OnLostKeyboardFocus"
  KeyDown="durationTextBox_OnKeyDown">10:12 min</toggl:ExtendedTextBox>
  - <StackPanel Orientation="Horizontal"
  - Grid.Row="1" Grid.Column="1">
  <toggl:ExtendedTextBox x:Name="startTimeTextBox" x:FieldModifier="private"
  + Grid.Row="1" Grid.Column="1"
  Style="{StaticResource {x:Type TextBox}}"
  - Margin="0 0 8 0" Width="64"
  LostKeyboardFocus="startTimeTextBox_OnLostKeyboardFocus"
  KeyDown="startTimeTextBox_OnKeyDown">12:45</toggl:ExtendedTextBox>
  - <ContentControl Focusable="False" Content="{StaticResource Toggl.ArrowIcon}" />
  + <ContentControl Focusable="False"
  + Margin="6 0"
  + Grid.Row="1" Grid.Column="2"
  + Content="{StaticResource Toggl.ArrowIcon}" />
  <toggl:ExtendedTextBox x:Name="endTimeTextBox" x:FieldModifier="private"
  + Grid.Row="1" Grid.Column="3"
  Style="{StaticResource {x:Type TextBox}}"
  - Margin="7 0 0 0" Width="64"
  LostKeyboardFocus="endTimeTextBox_OnLostKeyboardFocus"
  KeyDown="endTimeTextBox_OnKeyDown">12:55</toggl:ExtendedTextBox>
  - </StackPanel>
  - <DatePicker Name="startDatePicker" x:FieldModifier="private" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"
  + <DatePicker Name="startDatePicker" x:FieldModifier="private" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="4"
  Margin="0 8 0 0"
  Height="32" SelectedDate="05.01.2015" SelectedDateChanged="startDatePicker_SelectedDateChanged"/>
  </Grid>
  