UserControl hosted in Panel - wpf

Question

I've spent a lot of time with this problem. I have custom user control in wpf, It's toolbar with 10 buttons. This toolbar is added in Panel(winform panel) panel.Controls.Add(usercontrol). What I want is, respond on MouseLeave event from Panel.
I've tried panel.MouseLeave += MouseLeaveEvent, but event hasn't raised. No one event isn't raised(MouseMove, etc.). Is there any solution, how to make it, that MouseLeave event will be raised?
Thanks a lot.
EDIT
Here is the code.
CustomToolbar = new AxisMediaControlToolbarViewModel(this);
var toolbarView = new AxisMediaControlToolbarView { ViewModel = CustomToolbar };
var elementHost = new ElementHost { Dock = DockStyle.Fill, Child = toolbarView };
toolbarPanel.Controls.Add(elementHost);

Answer 1

In this thread are quite a few causes mentioned:
Set the Background of the UserControl
Make the Canvas focusable
Be aware of RenderTransforms
EDIT
I made a test and it works fine as long as the WPF element is not covering the Panel. The mouse has to be DIRECTLY over the panel to generate the event. The DockStyle.Fill might be the cause of your problem.

Answer 2

One of the causes may be that your panel's background is not set.
If you do not set the background, then the control is though to be as "its area is not to be taken care of" and effectively it is transparent, because it is not drawn. However, it has more consequences: it's area is not only not drawn, but also it is not tracked i.e. for mouse events.
For starters, try setting Background="Transparent". It may make little sense as it is already transparent, but this way the Panel control will have a background and if there are no other problems, it may immediatelly start seeing the mouse events.
edit: quickexample:
UserControl.xaml
<UserControl x:Class="UserControlMouse.MyButtonPanel"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
Background="LightBlue"
Tag="You will never see this message">
<StackPanel Margin="20" Background="LightGray"
MouseEnter="handler_MouseEnter" MouseMove="handler_MouseMove" MouseLeave="handler_MouseLeave"
Tag="StackPanel">
<StackPanel.Resources>
<Style TargetType="Border">
<Setter Property="Margin" Value="2" />
<Setter Property="Padding" Value="5" />
<Setter Property="Background" Value="Gray" />
</Style>
<Style TargetType="TextBlock">
<Setter Property="TextAlignment" Value="Center" />
<Setter Property="Background" Value="WhiteSmoke" />
</Style>
</StackPanel.Resources>
<Button Content="#1" MaxWidth="80" Tag="Button#1" />
<Button Content="#2" MaxWidth="80" Tag="Button#2"
MouseEnter="handler_MouseEnter" MouseMove="handler_MouseMove" MouseLeave="handler_MouseLeave"
/>
<Button Content="#3" MaxWidth="80" Tag="Button#3" />
<Button Content="#4" MaxWidth="80" Tag="Button#4" />
<Button Content="#5" MaxWidth="80" Tag="Button#5"
MouseEnter="handler_MouseEnter" MouseMove="handler_MouseMove" MouseLeave="handler_MouseLeave"
/>
<Button Content="#6" MaxWidth="80" Tag="Button#6" />
<Button Content="#7" MaxWidth="80" Tag="Button#7" />
<Button Content="#8" MaxWidth="80" Tag="Button#8" />
<TextBlock Margin="0,20,0,0" Tag="Comment TextBlock #1">
<Run Text="Sender was: " />
<Run Text="{Binding ReportingControl}" />
</TextBlock>
<TextBlock Tag="Comment TextBlock #2">
<Run Text="Source was: " />
<Run Text="{Binding ContainerControl}" />
</TextBlock>
<TextBlock Tag="Comment TextBlock #3">
<Run Text="Now you are in: " />
<Run Text="{Binding ControlUnderMouse}" />
</TextBlock>
<UniformGrid Columns="3" Tag="indicator UniformGrid">
<Border Visibility="{Binding Visib_OnEnter}" Tag="indicator border #1">
<TextBlock Text="Enter" />
</Border>
<Border Visibility="{Binding Visib_OnMove}" Tag="indicator border #2"
MouseEnter="handler_MouseEnter" MouseMove="handler_MouseMove" MouseLeave="handler_MouseLeave">
<TextBlock Text="Move" />
</Border>
<Border Visibility="{Binding Visib_OnLeave}" Tag="indicator border #3">
<TextBlock Text="Leave" />
</Border>
</UniformGrid>
</StackPanel>
</UserControl>
usercontrol.xaml.cs
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
namespace UserControlMouse
{
public partial class MyButtonPanel : UserControl
{
private SimpleDataObject theData = new SimpleDataObject();
public MyButtonPanel()
{
InitializeComponent();
this.DataContext = theData;
}
private const int COUNTER_LAG = 20;
private int counter_enter = 0;
private void handler_MouseEnter(object sender, MouseEventArgs e)
{
counter_enter = counter_mouse;
theData.Visib_OnEnter = System.Windows.Visibility.Visible;
theData.Visib_OnMove = System.Windows.Visibility.Hidden;
theData.Visib_OnLeave = System.Windows.Visibility.Hidden;
theData.ReportingControl = makeDescriptionOfControl(sender);
theData.ContainerControl = makeDescriptionOfControl(e.Source);
theData.ControlUnderMouse = makeDescriptionOfControl(null);
}
private int counter_mouse = 0;
private void handler_MouseMove(object sender, MouseEventArgs e)
{
++counter_mouse;
if (counter_mouse > counter_enter + COUNTER_LAG) theData.Visib_OnEnter = System.Windows.Visibility.Hidden;
theData.Visib_OnMove = System.Windows.Visibility.Visible;
if (counter_mouse > counter_leave + COUNTER_LAG) theData.Visib_OnLeave = System.Windows.Visibility.Hidden;
theData.ReportingControl = makeDescriptionOfControl(sender);
theData.ContainerControl = makeDescriptionOfControl(e.Source);
theData.ControlUnderMouse = makeDescriptionOfControl(null);
}
private int counter_leave = 0;
private void handler_MouseLeave(object sender, MouseEventArgs e)
{
counter_leave = counter_mouse;
theData.Visib_OnEnter = System.Windows.Visibility.Hidden;
theData.Visib_OnMove = System.Windows.Visibility.Hidden;
theData.Visib_OnLeave = System.Windows.Visibility.Visible;
theData.ReportingControl = makeDescriptionOfControl(sender);
theData.ContainerControl = makeDescriptionOfControl(e.Source);
theData.ControlUnderMouse = makeDescriptionOfControl(null);
}
private string makeDescriptionOfControl(object uiobj)
{
if (uiobj == null)
return "???";
string text = uiobj.GetType().Name;
var fe = uiobj as FrameworkElement;
if (fe != null && fe.Tag != null)
text += " (" + (string)((FrameworkElement)uiobj).Tag + ")";
return text;
}
}
public class SimpleDataObject : DependencyObject
{
public string ControlUnderMouse { get { return (string)GetValue(ControlUnderMouseProperty); } set { SetValue(ControlUnderMouseProperty, value); } }
public static readonly DependencyProperty ControlUnderMouseProperty = DependencyProperty.Register("ControlUnderMouse", typeof(string), typeof(SimpleDataObject), new UIPropertyMetadata("???"));
public string ReportingControl { get { return (string)GetValue(ReportingControlProperty); } set { SetValue(ReportingControlProperty, value); } }
public static readonly DependencyProperty ReportingControlProperty = DependencyProperty.Register("ReportingControl", typeof(string), typeof(SimpleDataObject), new UIPropertyMetadata("???"));
public string ContainerControl { get { return (string)GetValue(ContainerControlProperty); } set { SetValue(ContainerControlProperty, value); } }
public static readonly DependencyProperty ContainerControlProperty = DependencyProperty.Register("ContainerControl", typeof(string), typeof(SimpleDataObject), new UIPropertyMetadata("???"));
public Visibility Visib_OnEnter { get { return (Visibility)GetValue(Visib_OnEnterProperty); } set { SetValue(Visib_OnEnterProperty, value); } }
public static readonly DependencyProperty Visib_OnEnterProperty = DependencyProperty.Register("Visib_OnEnter", typeof(Visibility), typeof(SimpleDataObject), new UIPropertyMetadata(Visibility.Hidden));
public Visibility Visib_OnMove { get { return (Visibility)GetValue(Visib_OnMoveProperty); } set { SetValue(Visib_OnMoveProperty, value); } }
public static readonly DependencyProperty Visib_OnMoveProperty = DependencyProperty.Register("Visib_OnMove", typeof(Visibility), typeof(SimpleDataObject), new UIPropertyMetadata(Visibility.Hidden));
public Visibility Visib_OnLeave { get { return (Visibility)GetValue(Visib_OnLeaveProperty); } set { SetValue(Visib_OnLeaveProperty, value); } }
public static readonly DependencyProperty Visib_OnLeaveProperty = DependencyProperty.Register("Visib_OnLeave", typeof(Visibility), typeof(SimpleDataObject), new UIPropertyMetadata(Visibility.Hidden));
}
}
sample window
<Window x:Class="UserControlMouse.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="clr-namespace:UserControlMouse"
Title="MainWindow" Height="350" Width="525">
<Grid Background="Red">
<my:MyButtonPanel Margin="10" />
</Grid>
</Window>
Please run it and play with it.
Observe how the events are fired and which controls see them. Note how SENDER and SOURCE are changing
note that SENDER is always the same, the root of the mouse-capture. It is the Source that changes
note that only button #2 and button #5 is reporting ENTER/LEAVE (they have direct handlers, others have not!)
note that other controls are 'detectable' with the mouse-move even if they don't have mouse handlers - you can get events with Source(s) that does not have any mouse capture set
check the OriginalSource (the last text line) - this is the control directly under mouse - and often it is not the control you would want to notice, as it is some "leaf control" from some templates or styles..