With the below xaml, you will notice the the DatePicker cannot align to the left with the TextBox
<StackPanel>
<input:RadDatePicker Width="80" />
<input:RadDatePicker Width="80" />
<TextBox Text="test test" Width="80"/>
</StackPanel>
If you select a date in the date picker, you'll notice the text in DatePicker is also not left aligned with the text in the TextBox
<StackPanel>
<input:RadDatePicker Width="80" />
<input:RadDatePicker Width="80" />
<TextBox Text="test test" Width="80"/>
</StackPanel>
If you select a date in the date picker, you'll notice the text in DatePicker is also not left aligned with the text in the TextBox