allow multiline input on android

samples/MobileSandbox/MainView.xaml

@@ -5,8 +5,8 @@
              x:DataType="mobileSandbox:MainView">
   <StackPanel Margin="100 50" Spacing="50">
     <TextBlock Text="Login" Foreground="White" />
-    <TextBox Watermark="Text" />
-    <TextBox Watermark="Username" TextInputOptions.ContentType="Email" AcceptsReturn="True" TextInputOptions.ReturnKeyType="Search" />
+    <TextBox TextInputOptions.Multiline="True" AcceptsReturn="True" Watermark="Text" Height="200" TextWrapping="Wrap"/>
+    <TextBox Watermark="Username" TextInputOptions.ContentType="Email" TextInputOptions.ReturnKeyType="Done" />
     <TextBox Watermark="Password" PasswordChar="*" TextInputOptions.ContentType="Password" />
     <TextBox Watermark="Pin" PasswordChar="*" TextInputOptions.ContentType="Digits" />
     <Button Content="Login" Command="{Binding ButtonCommand}" />

src/Android/Avalonia.Android/AndroidInputMethod.cs

@@ -177,7 +177,8 @@ namespace Avalonia.Android
                     TextInputReturnKeyType.Search => (ImeFlags)CustomImeFlags.ActionSearch,
                     TextInputReturnKeyType.Next => (ImeFlags)CustomImeFlags.ActionNext,
                     TextInputReturnKeyType.Previous => (ImeFlags)CustomImeFlags.ActionPrevious,
-                    _ => (ImeFlags)CustomImeFlags.ActionDone
+                    TextInputReturnKeyType.Done => (ImeFlags)CustomImeFlags.ActionDone,
+                    _ => options.Multiline ? ImeFlags.NoEnterAction : (ImeFlags)CustomImeFlags.ActionDone
                 };
 
                 outAttrs.ImeOptions |= ImeFlags.NoFullscreen | ImeFlags.NoExtractUi;