Textbox two way binding not triggering - wpf

Question

I have a tab control with 3 objects, 2 lists and a textbox. The text box is bound two way :
<TabControl x:Name="tcTabs" ItemsSource="{Binding Rooms, UpdateSourceTrigger=PropertyChanged}" Margin="5" BorderThickness="1" IsSynchronizedWithCurrentItem="True">
<TabControl.ItemContainerStyle>
<Style TargetType="TabItem">
<Setter Property="Header" Value="{Binding Name}" />
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="22"/>
</Grid.RowDefinitions>
<ListBox ItemsSource="{Binding ReceivedMessages}" DisplayMemberPath="Raw" Grid.Row="0" Grid.Column="0" BorderThickness="0" />
<ListBox ItemsSource="{Binding Users}" DisplayMemberPath="Nick" Visibility="{Binding Type, Converter={StaticResource UserListVisibilityConverter}}" Grid.Row="0" Grid.Column="1" BorderThickness="1,0,0,0" BorderBrush="#FFBBBBBB" Width="130" />
<TextBox Text="{Binding CurrentInput, Mode="TwoWay"}" Grid.Row="1" Grid.ColumnSpan="2" BorderThickness="0,1,0,0" BorderBrush="#FFBBBBBB" Height="22" />
</Grid>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</TabControl.ItemContainerStyle>
</TabControl>
Backing object :
public string CurrentInput
{
get
{
return _currentInput;
}
set
{
if (value != _currentInput)
{
_currentInput = value;
OnPropertyChanged();
}
}
}
Problem is, when I change the text and click another tab it does not update the backing field (does not even hit the setter), however if I change then click the listbox it does...
Any reason for this odd behaviour?

Answer 1

That is not an odd behaviour and has been asked multiple times before. Read about Binding.UpdateSourceTrigger, also see the remarks of the respective property you bind.

Answer 2

I've solve this problem (Twoway Binding) by manual trigger the databinding engine using
DataContext = this;