WPF FAQ for me

1. Capture Mouse是怎么回事？

UIElement.CaptureMouse() and Mouse.Capture()
Capture mouse能够使 即使在控件之外也能够获取鼠标事件，拖，拉鼠标时最有用。
When an element captures the mouse, it receives mouse input whether or not the cursor is within its borders.

释放：UIElement.ReleaseMouseCapture() 或者Mouse.Capture(null)

注意只能获取MouseUp 与MouseDown事件，其他的如MouseLeftUp与MouseLeftDown不能获取

2. XAML中的Uid是做什么用的？

x:Uid Attribute

x:Uid Attribute是XAML中唯一的特例：它可以放在一个property element中，任何其他的attribute放在property 元素上都是非法的。它是被Localization 进程或者工具使用的。

3. 如何理解GridUnitType

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="350" Margin="0,0,0,0">
    <Grid ShowGridLines="True" Width="300">
        <!--the availabe width for this grid is 300 pixel-->
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"></ColumnDefinition>
            <!--The width of this column is determined by its content, its 20pixel-->
            <ColumnDefinition Width="2*"></ColumnDefinition>
            <!--the remaining space is 280pixel(300-20),divided by 6,this column will have 2*(280/6)=93-->
            <ColumnDefinition Width="3*"></ColumnDefinition>
            <ColumnDefinition Width="1*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Button Width="20" Grid.Column="0"></Button>
        <!--the width of this button determine the width of first column-->
    </Grid>
</Window>