[wpf] Align items in a stack panel?

I was wondering if I can have 2 controls in a horizontal-oriented StackPanel so that the right item should be docked to the right side of the StackPanel.

I tried the following but it didn't work:

<StackPanel Orientation="Horizontal">
    <TextBlock>Left</TextBlock>
    <Button Width="30" HorizontalAlignment="Right">Right<Button>
</StackPanel>

In the snippet above I want the Button to be docked to the right side of the StackPanel.

Note: I need it to be done with StackPanel, not Grid etc.

for windows 10 use relativePanel instead of stack panel, and use

relativepanel.alignrightwithpanel="true"

for the contained elements.

This works perfectly for me. Just put the button first since you're starting on the right. If FlowDirection becomes a problem just add a StackPanel around it and specify FlowDirection="LeftToRight" for that portion. Or simply specify FlowDirection="LeftToRight" for the relevant control.

<StackPanel Orientation="Horizontal" HorizontalAlignment="Right" FlowDirection="RightToLeft">
    <Button Width="40" HorizontalAlignment="Right" Margin="3">Right</Button>
    <TextBlock Margin="5">Left</TextBlock>
    <StackPanel FlowDirection="LeftToRight">
        <my:DatePicker Height="24" Name="DatePicker1" Width="113" xmlns:my="http://schemas.microsoft.com/wpf/2008/toolkit" />    
    </StackPanel>
    <my:DatePicker FlowDirection="LeftToRight" Height="24" Name="DatePicker1" Width="113" xmlns:my="http://schemas.microsoft.com/wpf/2008/toolkit" />    
</StackPanel>

Maybe not what you want if you need to avoid hard-coding size values, but sometimes I use a "shim" (Separator) for this:

<Separator Width="42"></Separator>

Yo can set FlowDirection of Stack panel to RightToLeft, and then all items will be aligned to the right side.

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <TextBlock Text="Left"  />
    <Button Width="30" Grid.Column="1" >Right</Button>
</Grid>

Could not get this working using a DockPanel quite the way I wanted and reversing the flow direction of a StackPanel is troublesome. Using a grid is not an option as items inside of it may be hidden at runtime and thus I do not know the total number of columns at design time. The best and simplest solution I could come up with is:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="Auto" />
    </Grid.ColumnDefinitions>
    <StackPanel Grid.Column="1" Orientation="Horizontal">
        <!-- Right aligned controls go here -->
    </StackPanel>
</Grid>

This will result in controls inside of the StackPanel being aligned to the right side of the available space regardless of the number of controls - both at design and runtime. Yay! :)

For those who stumble upon this question, here's how to achieve this layout with a Grid:

<Grid>
    <TextBlock Text="Server:"/>
    <TextBlock Text="http://127.0.0.1" HorizontalAlignment="Right"/>
</Grid>

creates

Server:                                                                   http://127.0.0.1

If you are having a problem like the one I had where labels were centered in my vertical stack panel, make sure you use full width controls. Delete the Width property, or put your button in a full-width container that allows internal alignment. WPF is all about using containers to control the layout.

<StackPanel Orientation="Vertical">
    <TextBlock>Left</TextBlock>
    <DockPanel>
        <Button HorizontalAlignment="Right">Right</Button>
    </DockPanel>
</StackPanel>

Vertical StackPanel with Left Label followed by Right Button

I hope this helps.