Odd behavior with rowless and columness children items in a grid

Question

Consider this simple Grid:

<Grid x:Name="gridTest" ShowGridLines="True">
    <Grid.RowDefinitions>
        <RowDefinition></RowDefinition>
        <RowDefinition></RowDefinition>
        <RowDefinition></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition></ColumnDefinition>
        <ColumnDefinition></ColumnDefinition>
        <ColumnDefinition></ColumnDefinition>
    </Grid.ColumnDefinitions>
</Grid>

In code-behind, I add this code:

public MainWindow()
{
    InitializeComponent();

    Label labTest = new Label { Content = "Test Label" };
    gridTest.Children.Add(labTest);
}

The result is:

Note the label is on top left of the grid. Its ok because I dont set the Grid.Col and Grid.Row (using Grid.SetColumn() and Grid.SetRow())

Now, check the next example:

public MainWindow()
{
    InitializeComponent();

    Label labTest = new Label { Content = "Test Label", Height = 30, Width = 70 };
    gridTest.Children.Add(labTest);
}

I simply added a height and width for the label. But the result is:

Now, the label acts like centralized in the first cell of the grid although I didnt specify Grid rows or cols for the label! My questions:

Why this happens? Is it "by design" or its a bug?
What can I do to the label in the second example to act like in the first, i.e. appears on topmost and leftmost (0,0) location of the grid when added to grid.Children collection?

BoltClock BoltClock · Accepted Answer · 2018-01-30T05:25:27

It's by design. The label is in fact always centralized in the first cell of the grid. You just don't see it without giving it dimensions because it fills up the entire cell by default, but its content remains left-aligned at all times.

Align the label itself using its VerticalAlignment and HorizontalAlignment attributes:

Label labTest = new Label
{
    Content = "Test Label",
    Height = 30,
    Width = 70,
    VerticalAlignment = VerticalAlignment.Top,
    HorizontalAlignment = HorizontalAlignment.Left
};
gridTest.Children.Add(labTest);

Odd behavior with rowless and columness children items in a grid

1 Answers