Xamarin.Forms 2.3.1.110-pre1

# 2.3.1-pre1 ## Important notes When upgrading Xamarin.Forms take care not to simply "update all" as that will update the Xamarin.Android.Support packages to an incompatible version. More info [here](https://developer.xamarin.com/guides/xamarin-forms/troubleshooting/). ## New Features * Added `KeyboardFlags.None` enum value and added `Keyboard.Plain` which uses `KeyboardFlags.None` for its implementation. * Added `GridLength.Star` as a convenience value to complement the existing `GridLength.Auto` ## Bugs Fixed * [27417](https://bugzilla.xamarin.com/show_bug.cgi?id=27417) - "Button.Image behaviors differently on each platform and has extra padding even with no Text" Fix: When an image and no text is specified for an image, the image position should default to centered (vertically and horizontally). This fixes a bug in the Android logic which leaves images aligned near the top of the button when the button is sufficiently taller than the image. * [31809](https://bugzilla.xamarin.com/show_bug.cgi?id=31809) - "PopToRootAsync isn't working in my Windows Phone Runtime(8.1) project" Fix: When callingPopToRootAsync on 8.1/UWP, the navigation stack was being cleared, but the current page wasn't actually being set, so a crash would subsequently occur if attempting to call it again, for example. This was due to a missing event handler on the NavigationPageRenderer which sets the page to the expected root. * [33507](https://bugzilla.xamarin.com/show_bug.cgi?id=33507) - "Android: "System.ArgumentException: 'jobject' must not be IntPtr.Zero" when setting Focus for Picker = True" Fix: ViewRenderer failed to unsubscribe from FocusChangeRequested on disposed and so attempted to dispatch a focus change request to a disposed renderer. * [36447](https://bugzilla.xamarin.com/show_bug.cgi?id=36447) - "[Android] PinchGestureRecognizer Only Works on Android API Level 19+" Fix: Fix usage of a API18 only constructor on ScaleGestureDetector * [37862](https://bugzilla.xamarin.com/show_bug.cgi?id=37862) - "ListView with CachingStrategy=recycleElement Doesn't respect HasUnevenRows=True " Fix: Don't use the fixed LayoutConstraint when using uneven rows. We were using a fixed LayoutConstraint for the viewcell view, this caused Grid't using '*' (star) to skip computing the size of it's children and returning the cached value. * [38284](https://bugzilla.xamarin.com/show_bug.cgi?id=38284) - "when creating a map in iOS, if the map is not visible when the page is created the zoom level is off" Fix: Update the current region of the MKMapView when visible. If the iOS MKMapView is invisible it will update it's region because there's no Frame/Bounds for calculation. We need to make sure we update the current region when the map is visible again. * [39187](https://bugzilla.xamarin.com/show_bug.cgi?id=39187) - "UWP Navigation shows duplicate page when performing multiple nav operations" * [39486](https://bugzilla.xamarin.com/show_bug.cgi?id=39486) - "HasUnevenRows=true ignored in Forms iOS project in TableView with CustomCell; row heights are not auto-sized" * [39802](https://bugzilla.xamarin.com/show_bug.cgi?id=39802) - "Gap between ListView cells even if SeparatorVisablity is set to none" * [40005](https://bugzilla.xamarin.com/show_bug.cgi?id=40005) - "[Android] Navigation Bar back button does not show when using InsertPageBefore(insertedPage, page1) to add a page to the stack before the first page." * [40333](https://bugzilla.xamarin.com/show_bug.cgi?id=40333) - "[Android] IllegalStateException: Recursive entry to executePendingTransactions" * [40639](https://bugzilla.xamarin.com/show_bug.cgi?id=40639) - "Xamarin.Forms 2.1.0.6529 (Android only). Unhandled Exception: Java.Lang.IllegalStateException: Recursive entry to executePendingTransactions when switching MainPage or children of TabbedPage in FormsAppCompatActivity" * [40704](https://bugzilla.xamarin.com/show_bug.cgi?id=40704) - "Strange duplication of listview headers when collapsing/expanding sections" * [40740](https://bugzilla.xamarin.com/show_bug.cgi?id=40740) - "UWP Platform constructor throws TypeLoadException." Modified calls to ApiInformation.IsTypePresent() in WinRT Platform.cs to compile and run when theStatusBar type is not present. * [40830](https://bugzilla.xamarin.com/show_bug.cgi?id=40830) - "AppLinkEntry.KeyValues collection is always empty" * [40866](https://bugzilla.xamarin.com/show_bug.cgi?id=40866) - "RegisterLink throws an ArgumentException on Android" * [40998](https://bugzilla.xamarin.com/show_bug.cgi?id=40998) - "Hitting Esc when an action sheet displayed on UWP does not result in the await returning" Fix: On UWP, when DisplayActionSheet is being awaited, pressing escape while the ActionSheet is visible would cause it to disappear but not actually return any result. Checking for an escape keypress in the window and setting the result to ContentDialogResult.None (as no button was tapped) returns a result as expected. * [41038](https://bugzilla.xamarin.com/show_bug.cgi?id=41038) - "MasterDetailPage loses menu icon on iOS after reusing NavigationPage as Detail" Fix: When a page is being removed we need to make sure we update the left toolbar item to show the master icon or text. We need to pas a reference of the remove page, because the NavigationPage still has that page in the navigation stack, the event fires on the renderer before it's removed from the internal children. * [41076](https://bugzilla.xamarin.com/show_bug.cgi?id=41076) - "App Resume hangs on WP 8.1 (Silverlight)" * [41078](https://bugzilla.xamarin.com/show_bug.cgi?id=41078) - " [Win 8.1] ListView not visually setting the initially selected item upon creation" Fix: On Windows 8.1, when the SelectedItem property on a ListView was set prior to the page it was contained in displaying, there was no indication of that item being selected (although the value was set) when the page eventually displayed. This is normally indicated via a background color on the cell. Subsequent selections of other items would cause the visual indication to work as expected. Explicitly calling OnElementItemSelected in OnElementChanged if the SelectedItem value has been set resolves this. * [41241](https://bugzilla.xamarin.com/show_bug.cgi?id=41241) - "Custom Button Image Missized in Xamarin Forms Cross-platform in the WinPhone App" Fix: Previously, the Windows platforms hard-coded the size of button images to 30x30; this meant that larger images on buttons could not be displayed and smaller images were scaled up. This change removes the hard-coded size and uses the actual size of the image when laying out the button. * [41296](https://bugzilla.xamarin.com/show_bug.cgi?id=41296) - "MarkupExtension not found in default namespace" * [41404](https://bugzilla.xamarin.com/show_bug.cgi?id=41404) - "Xamarin Forms Master Page (of Master Detail Page) obscures Android status bar with Material Design" * [41424](https://bugzilla.xamarin.com/show_bug.cgi?id=41424) - "DatePicker doesn't lose focus on Cancel" * [41842](https://bugzilla.xamarin.com/show_bug.cgi?id=41842) - "Set MasterDetailPage.Detail = New Page() twice will crash the application when set MasterBehavior = MasterBehavior.Split" Fix: MasterDetailControl will no longer null out the TCS before it is used. Failure only occurs when the MainPage is swapped out and the Detail page is changed twice. UI test doesn't cover this scenario. * [41854](https://bugzilla.xamarin.com/show_bug.cgi?id=41854) - "[UWP] NavigationPage back button remains when resetting Application.Curent.MainPage to ContentPage" ### Other fixes * [Android] Isolate fragment management for children of MasterDetailPage * [Android] Can't reset BarTextColor to default on TabbedPage. Fix: storing default color for TabbedPage bar text on Android so we can reset it if necessary. * [Android] Fix android StartTimer race condition. This fixes the GREF issue reported by the Android team against Cycle 7 * [iOS] Set the frame of a cell NativeView using the calculated positions and size * [iOS] Rotation and orientations methods now correctly forwarded in iOS. Allows programmatic rotation locking of screen. * [UWP] Make wrapper of a ViewCell respect margins * [WinRT/UWP] Center crop image on AspectFill to provide same experience that Android and iOS curently provide. * [WinRT] Add base platform as inner proxy navigation to Application, Fix back button issue [see 39187, 41854] * [XAML] fix Thickness.IsDefault. Bottom was ignored * Isolate fragment management for children of MasterDetailPage. If an AppCompat MasterDetailPage hosts NavigationPages or TabbedPages in either the Master or Detail sections, those pages are now wrapped in their own Fragment (and use that Fragment's ChildFragmentManager) to isolate their Fragment management operations and avoid recursive entry into the executePendingTransactions() method. Also fixed a disposal bug in the custom MDP renderer in Control Gallery. [see 40333, 40639] * Implemented the AppIndexProvider on non-AppCompact backend to fix bug on KeyValues on AppLinkEntry [see 40866, 40830] * Backend renderers now implement the correct position and size of the View of a ViewCell * Allow Registrar.RegisterAll to be invoked multiple times without causing exception * Data Pages docs added * Numerous small doc fixes * Added Mailing List info to the README.md For full details on changes: [https://github.com/xamarin/Xamarin.Forms/compare/2.3.0...beta-2.3.1-pre1]