WPF - setting HorizontalAlignment= Stretch to Textbox in StackPanel

Question

Why doesn't a textbox stretch to fill space in a stackpanel? Is this by design? In a grid, the textbox stretches as expected.

Answer 1

Yes, it's by design. The StackPanel will allocate the space the TextBox asks for. If you haven't set a width on the TextBox, it will require only enough width to fit its text.

Answer 2

Kent's answer seems right.
To still force override the StackPanel behavior, I think you'd need to dynamically compute-set the Width property of the contained elements OR some funky override of MeasureOverride. I'd rather use another layout manager/panel. Some things I noted..

• The default value for HorizontalAlignment and VerticalAlignment properties of child elements is Stretch (if you don't specify one explicitly).

• The StackPanel will stretch elements based on its Orientation property value. So

  • Orientation=Horizontal means all elements will be vertically stretched to max. Elements flow horizontally.
  • Orientation=Vertical means all elements will be horiz stretched to max. Elements flow vertically.
• Unless explicitly specified, Width and Height of child elements are NaN. If you specify an explicit value, StackPanel will honor them over the Horiz and Vert Alignment settings.
• The StackPanel itself has HorizontalAlignment and VerticalAlignment that adds a further layout twist. You can experiment with this example.

StackPanel

The default value is stretch for both HorizontalAlignment and VerticalAlignment of content that is contained in a StackPanel.

HorizontalAlignment

When Height and Width properties are explicitly set on an element, these measurements take higher precedent during layout and will cancel the typical effects of setting HorizontalAlignment to Stretch.

Answer 3

I needed items to be sized evenly, but stacked vertically.

I used a UniformGrid, and set the Columns property to 1. (tested with a TextBox, and it stretches like you want)