Develop Reference

Need to modfy the default tab order of child elements

I have custom control like below. When press tab key focus will move in the order elements arrangement.
Query:
When stackpanel receive tab focus I need to change default tab order toggle button present in stackpanel
Default Tab Order:
DockPanel--Border---StackPanel-->Button1-->button2-->button3
Expected Order
DockPanel--Border---StackPanel-->Button3-->button2-->button1
I need update TabOrder based on its parent. Please suggestion solution modify the tab order based on parent
Note: I need UI as like below arrangements, only i need to modify the tab order for buttons
<DockPanel VerticalAlignment="Center" HorizontalAlignment="Center">
<Border x:Name="MainBorder">
<StackPanel>
<ToggleButton>Button 1</ToggleButton>
<ToggleButton>Button 3</ToggleButton>
<ToggleButton>Button 3</ToggleButton>
</StackPanel>
</Border>
</DockPanel>

As mentioned in comments do set the TabIndex property. To step within control do use KeyboardNavigation.TabNavigation attached property.
<DockPanel VerticalAlignment="Center" HorizontalAlignment="Center">
<Border x:Name="MainBorder">
<StackPanel KeyboardNavigation.TabNavigation="Local">
<ToggleButton KeyboardNavigation.TabIndex="3">Button 1</ToggleButton>
<ToggleButton KeyboardNavigation.TabIndex="2">Button 2</ToggleButton>
<ToggleButton KeyboardNavigation.TabIndex="1">Button 3</ToggleButton>
</StackPanel>
</Border>
</DockPanel>
If you want to modify the tab order at run time I would advice you to create a behavior for it. See Use of Behavior in WPF MVVM? To access attached property from code see Get and set WPF custom attached property from code behind

Use ScrollBar in DropDownButton?

I want use a scrollbar like ComboBox in my DropDown button, the structure actually is this:
<Controls:DropDownButton Content="Nazioni" Width="120" Margin="0, 0, 20, 0"
ScrollViewer.VerticalScrollBarVisibility="Visible"
ScrollViewer.CanContentScroll="True"
ItemsSource="{Binding Countries}"
ItemTemplate="{StaticResource CombinedTemplate}"/>
but I don't see any ScrollViewer as you can see in the image below:

The drop-down of the DropDownButton already contains a ScrollViewer (it is named "SubMenuScrollViewer"), so scrolling through its items is supported out-of-the-box. The thing is, that particular ScrollViewer is styled differently than a default ScrollViewer - assuming we're talking about vertical scrolling, it has two buttons above and below the list, responsible for scrolling up and down respectively, as shown below:
So your best bet is to make that particular ScrollViewer use the default style rather than a custom one. By inspecting the MahApps.Metro source code we can see that the ScrollViewer in question is wired to use a dynamic resource with a key value of {ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}. So what you need to do is to supply a default style with that key for that control:
<Controls:DropDownButton (...)>
<Controls:DropDownButton.Resources>
<Style x:Key="{ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}"
TargetType="{x:Type ScrollViewer}"
BasedOn="{StaticResource {x:Type ScrollViewer}}" />
</Controls.DropDownButton.Resources>
</Controls.DropDownButton>
This way the ScrollViewer within the drop-down will be styled with a default style shipped with MahApps.Metro.

To be certain that scrolling will behave as expected, you cannot rely on WPF to place a ScrollViewer where it should be.
As any content can be place on the dropdown, your best option is to drop a ScrollViewer straight onto the component.
This way, you can explicitly name it, and have access to its properties.
If you bind your list of countries to the lstContent box, you do away with all the messing.
<extToolkit:DropDownButton Content="Click Me" Margin="15" >
<extToolkit:DropDownButton.DropDownContent>
<ScrollViewer>
<ListBox Name="lstContent" ItemsSource="{Binding Countries}" ItemTemplate="{StaticResource CombinedTemplate}"/>
</ScrollViewer>
</extToolkit:DropDownButton.DropDownContent>
</extToolkit:DropDownButton>

Dragablz TabablzControl Visibility property not working

I'm using dragablz:TabablzControl in a project of mine and I have the need of hide/show some tabs dinamically.
The fact is the control is not respecting the property Visibility of the TabItem.
I've tried with and without binding, like this:
<dragablz:TabablzControl Grid.Row="2" BorderThickness="0" FixedHeaderCount="20">
<TabItem Header="Additional Info" Visibility="{Binding ShowAdditionalInfoTab, Converter={StaticResource BooleanToVisibilityConverter}}">
<controls:AdditionalInfoControl />
</TabItem>
<TabItem Header="Additional Info" Visibility="Collapsed">
<controls:AdditionalInfoControl />
</TabItem>
</dragablz:TabablzControl>
But none is working. Change the "FixedHeaderCount" does not affect the result.
The tab remains always visible.
Is there any other way that I can achieve the result I need?

I've received a response from the development team, and I'm leaving it here for anyone who has the same problem.
Yeah, obviously there’s since changes to the standard tab control to support all of the extra features, and currently that’s not supported. You’d have to temporarily remove your hidden item from the source.

TextBox vertical alignment in Windows Store App

I'm trying to do something that seems quite simple but that I haven't been able to do so far : Vertically align the text in a TextBox in Windows Store App (XAML).
VerticalContentAlignment doesn't work (although it works well in WPF). I've even tried to extract the template and change it. Still couldn't do it.
Does anyone know how to do it ?

Unfortunately there is no simple way. However if your TextBox has a fixed size then you can adjust the Padding Property in a custom style, it can be done dynamically too, but it is a bit more work.
<Style TargetType="TextBox" x:Key="CustomTextBoxStyle">
<Setter Property="Padding"
Value="25" />
</Style>
<TextBox Text="TestText"
Height="80"
Style="{StaticResource CustomTextBoxStyle}" />

Also you can try this one also...
<Grid>
<TextBox Text="Centered Text" TextAlignment="Center" VerticalAlignment="Center"/></Grid>

Disable Drag-drop from TextBox

I have a WPF textBox that is declared as ReadOnly
<TextBox IsReadOnly="True" IsTabStop="False" Width="200" />
So, User can not write anything into the TextBox or delete the content but it still allows user to drag the text from this textbox and drop it in any other textbox that caused the text removed from the first textbox(the read-only one) and thats unexpected. Is it a bug?
how can I get rid of this?

I tried the following code :
<StackPanel>
<TextBox IsReadOnly="True">Hello</TextBox>
<TextBox></TextBox>
</StackPanel>
When I drag-and-drop the text (after selection) from the first TexbtBox to the second one, the text is copied, but not removed from the first TextBox. I tried it under .NET 3.5 and .NET 4.0 targets.
If you want to get rid of your bug without trying to understand it (since it shouldn't happen), you can just put an empty control (Canvas will be ok) on top of your TextBox, with its Background property set to transparent.
<Grid>
<TextBox IsReadOnly="True" IsTabStop="False" Width="200" />
<Canvas Background="Transparent"/>
</Grid>
But the text won't be selectable anymore...