feat: add TextBox Demo, fix RadioButton demo. Add Borderless Theme.

src/Semi.Avalonia.Demo/Pages/Overview.axaml

@@ -3,7 +3,7 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" d:DesignHeight="450"
     d:DesignWidth="800" mc:Ignorable="d">
-    <ScrollViewer>
+    <ScrollViewer HorizontalScrollBarVisibility="Auto">
         <StackPanel Margin="10" Spacing="5">
             <TextBlock
                 HorizontalAlignment="Center" Classes="H4"
@@ -102,6 +102,12 @@
                     <TextBlock>Shadow</TextBlock>
                 </Border>
             </Grid>
+            <StackPanel Spacing="20">
+                <TextBox InnerLeftContent="http://" InnerRightContent=".com" />
+                <TextBox
+                    Classes="revealPasswordButton" PasswordChar="*"
+                    Text="Avalonia" />
+            </StackPanel>
         </StackPanel>
     </ScrollViewer>
 </UserControl>

src/Semi.Avalonia.Demo/Pages/RadioButtonDemo.axaml

@@ -14,8 +14,8 @@
         <TextBlock Text="Radio Button as Button" />
         <Border HorizontalAlignment="Left" Theme="{StaticResource RadioButtonGroupBorder}">
             <StackPanel Orientation="Horizontal">
-                <RadioButton Classes="Small" >小1</RadioButton>
-                <RadioButton Classes="Small" >小2</RadioButton>
+                <RadioButton Classes="Small" Theme="{DynamicResource ButtonRadioButton}">小1</RadioButton>
+                <RadioButton Classes="Small" Theme="{DynamicResource ButtonRadioButton}">小2</RadioButton>
             </StackPanel>
         </Border>
         <Border HorizontalAlignment="Left" Theme="{StaticResource RadioButtonGroupBorder}">

src/Semi.Avalonia.Demo/Pages/TextBoxDemo.axaml

@@ -17,6 +17,10 @@
             <TextBox
                 Width="300" Classes="revealPasswordButton"
                 PasswordChar="*" />
+            <TextBox
+                Width="500" InnerLeftContent="http://"
+                InnerRightContent=".com"
+                Theme="{StaticResource BorderlessTextBox}" />
         </StackPanel>
     </ScrollViewer>
 </UserControl>

src/Semi.Avalonia.Demo/Program.cs

@@ -1,5 +1,6 @@
 using Avalonia;
 using System;
+using Avalonia.Media;
 
 namespace Semi.Avalonia.Demo
 {
@@ -10,6 +11,16 @@ namespace Semi.Avalonia.Demo
         // yet and stuff might break.
         [STAThread]
         public static void Main(string[] args) => BuildAvaloniaApp()
+            .With(new FontManagerOptions
+            {
+                FontFallbacks = new[]
+                {
+                    new FontFallback
+                    {
+                        FontFamily = new FontFamily("Microsoft YaHei")
+                    }
+                }
+            })
             .StartWithClassicDesktopLifetime(args);
 
         // Avalonia configuration, don't remove; also used by visual designer.