Window animation interferes with WindowsFormsHost positioning

[barbeque]

When you put a WindowsFormsHost inside a Metro window, sometimes the WinForms control will occasionally 'hang' in space after the introductory animation has completed and only move once an event (such as hovering over the 'close' box or tabbing out of the MaskedTextBox) has been processed.

The actual control in question doesn't seem to matter; I've experienced it with Button, MaskedTextBox and CheckedListBox off the top of my head. It also happens if the WindowsFormsHost is located inside of a StackPanel or even the root Content control, not just the nested GroupBox described in the example XAML.

The test XAML to produce this window is:

    <metro:MetroWindow x:Class="MetroDemo.DemoWindow2"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:metro="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
            xmlns:wfh="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
            Title="Demo window 2" Height="500" Width="400">
        <DockPanel LastChildFill="True">
            <StackPanel Orientation="Vertical" DockPanel.Dock="Bottom">
                <GroupBox Header="WinForms Controls">
                    <StackPanel Orientation="Vertical">
                        <WindowsFormsHost Width="100" HorizontalAlignment="Left">
                            <wfh:MaskedTextBox Mask="00/000/0000"/>
                        </WindowsFormsHost>
                    </StackPanel>
                </GroupBox>
            </StackPanel>
        </DockPanel>
    </metro:MetroWindow>

I believe it is animation related because setting WindowTransitionsEnabled to false fixes the problem.

I am using v1.1.2.0, grabbed from NuGet yesterday. OS is Windows 8.1 x64.

[kjeremy]

I see this too on Windows 7

[punker76]

@barbeque I added a TransitionCompleted event to MetroContentControl and WindowTransitionCompleted event to MetroWindow which will be fired after the loaded Storyboard is completed. So you can subscribe to this event and can fire InvalidateVisual() (@petvetbr suggested this in #2394). This will be available in 1.5.0.
/cc @kjeremy